5 101 -268

Department of Energy

Flat-Plate Solar Array Project

25th Project Integration Meeting

Handout

•

California Institute of Technology June 19 and 20, 1985

Jet Propu lsion Laboratory

Cal ifornia Institute of Technology ·

Pasadena, Ca lifornia

JPL D-2404

Prepared by the Jet Propulsion Laboratory, California Institute of Technology, for the U.S. Department of Energy through an agreement with the National Aeronautics and Space Administration.

The JPL Flat-Plate Solar Array Project is sponsored by the U.S. Department of Energy and is part of the Photovoltaic Energy Systems Program to initiate a major effon toward the development of cost-competitive solar arrays.

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, com­pleteness, or usefulness of any information, apparatus, product, or process disclosed, or represents ·that its use would not infringe privately owned rights.

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer. or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This publication reports on work done under NASA Task RE-152, Amendment 66, DOE/ NASA IAA No. DE-AI01-76ET203S6.

REMINDER: Please bring this Handout

with you to the PIM

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5101-268

Department of Energy

Flat-Plate Solar Array Project

25th Project Integration Meeting

Handout

California Institute of Technology June 19 and 20, 1985

. Jet Propulsion Laboratory California Institute of Technology

Pasadena, California JPL D-2404

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Flat-Plate Solar Array Project Organization

DOE PROGRAlff EL-EMElvTS

1 Single-Junction .... Thin Alrns .... .... Silicon

Materials

Advanced Silicon Sheet

Flat-Plate Collector Research

Module Reliability

MATERIALS & DEVICES

AREA

M. Leipold Manager

Silicon Materials

Task {.4. Morrison)

Advanced Silicon Sheet Task

(A. Morrieon)

Device Research

Task {A. Kachare}

PROJECT MANAGEMENT W. Callaghan, Manager

D. Tustin, Administrative Manager

PROCESS DEVELOPMENT

AREA

D. Bickler Manager

Amorphous­Silicon

Deposition Task

High­Efficiency Processes

Task

RELIABILITY & ENGINEERING

SCIENCES AREA R. Ross Manager

Thin-Film Testing

Task

Advanced Module

Development Task

Module Reliability

Task

PROJECT ANALYSIS &

INTEGRATION AREA

P. McGuire Manager·

Project Analysis & Integration

Task

[]

CONTENTS

INTRODUCTION . .

INFORMATION . .

HAP: Meeting Location ..

AGENDA ......... .

ADVANCED SILICON SHEET AGENDA

NODULE DEVELOPMENT AND ENGINEERING SCIENCES AGENDA ..

PROCESS DEVELOPMENT AGENDA ....... .

HIGH-EFFICIENCY DEVICE RESEARCH AGENDA.

RELIABILITY PHYSICS AGENDA .....

SILICON MATERIAL AND JPL WEB TEAM

TECHNICAL SUMMARIES

In-House Surrmaries.

Amorphous Metals ...

Amorphous Silicon Deposition ..

Characterization of Silicon Sheet Material.

Defect Characterization of Silicon Dendritic Web Ribbons

Devices and Measurements Research Task.

Module and Array Engineering Sciences ..

Module Performance and Failure Analysis

Project Analysis and Integration ..

Reliability Physics ...... .

Silicon Materials Processing Research

Contractor Sunmaries ...

Applied Solar Energy Corp. & University of Illinois

ARCO Solar, Inc.: Pulsed Excimer Laser Processing for Cost-Effective Solar Cells .............. .

Clemson University: Investigation of Accelerated Stress Factors and Failure/Degradation Mechanisms in Terrestrial Solar Cells . . . . . . . . . . . . . . . . . . . .

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Cornell University: Electrical, Structural and Chemical Characterization of Silicon Sheet Material ...... . 32

Hughes Aircraft Co.: Amorphous Silicon Photovoltaic Modules and Test Devices ..................... . 33

Mobil Solar Energy Corp.: EFG Silicon ...... .

Stress and Efficiency Studies in 34

Purdue Research Foundation: HOD Silver Metallization for Photovoltaics ...... . 35

Purdue Research Foundation: Ink Jet Printing of Silver Metallization for Photovoltaics ........... . 36

Research Triangle Institute: High-Efficiency Solar Cell Design Modeling ................... . 37

Solarex Corp.: Block V Documentation and Solar Cell Modules 38

Spire Corp.: High-Efficiency Solar Cell Modules ..... .

Spire Corp.: Adapt Pulse Excimer Laser Processing Technology to Fabricate Cost-Effective Solar Cells ........... .

Springborn Laboratories: Investigation of Test Methods, Material Properties and Processes for Solar Cell Encapsulants .

State University of New York at Albany: Studies of Oxygen-and Carbon-Related Defects in High-Efficiency Silicon Solar Cells . . . . . . . . . . . . . . . . . . . . . .

Union Carbide Corp.: Fluid-Bed Silane Decomposition R&D

University of Florida: Physics of Heavily Doped Silicon and Solar-Cell Parameter Measurements ...... .

University of Illinois at Chicago: Surface Property Modification of Semiconductors by Fluid Adsorption.

University of Kentucky: Stress-Strain Analysis of Silicon Ribbon . . . . . . . . . . . . . . . . . . . . . . . . . .

University of Pennsylvania: Development and Analysis of Silicon Solar Cells of Near 20% Efficiency ...... .

University of Washington, JCGS: Efficiency Silicon Solar Cells

Investigation of High-

Westinghouse Advanced Energy Systems Division: Advanced Web Growth Development ............. .

Westinghouse Electric Corp.: Oendritic Web-Type Solar Cell Mini-Nodules .....

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Westinghouse R&D Center: Development of High-Efficiency Solar Cells on Silicon Web ...... .

FSA PROJECT ACTIVE CONTRACT STATUS LIST

FSA PUBLIC DOCUMENTS.

HAP: Pasadena Area ..

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Inside Back Cover

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INTRODUCTION

The Department of Energy (DOE)-Jet Propulsion Laboratory Flat-Plate Solar Array Project (FSA) will conduct its 25th Project Integration Meeting (PIK) June 19-20, 1985 (Wednesday and Thursday), at the California Institute of Technology (Ramo Auditorium), in Pasadena, California.

The theme for the 25th PIM is Progress in Processing of Higher-Efficiency, Low-Cost Solar Cells.

During the last few years, significant advances have been made in increasing laboratory crystalline-silicon solar-cell efficiencies. Recently a concerted experimental and analytical effort has been made to increase large-area crystalline-silicon solar-cell efficiency, using low-cost silicon sheet, and to understand how various factors control cell efficiency and how cell efficiency can be further increased. Solar-cell designs that result in higher efficiencies continue to evolve as knowledge of promising device structures and of silicon sheet and large-area cell interrelationships are better understood. Progress in combining this new knowledge with new processing technologies, such as excimer lasers, and development of processes that will increase the efficiency of large-area crystalline-silicon solar cells, has been limited. There is a need to understand the untapped potential capabilities better and to define limitations of these new processes. These subjects will be covered during the PIM.

Should you have questions or comments regarding the PIM, call Elmer Christensen (818) 577-9077 or Mary Phillips (818) 577-9096.

1

INFORMATION

CHECK IN: Please check in at the registration desk (lobby of Ramo Auditorium) at 7:30 a. m. Wednesday, June 19th, before the meeting to receive your badge or if you have not already registered to have a badge prepared for you.

TELEPHONE MESSAGES: Incoming calls to participants are to be placed through (818) 577-9520. These calls will be transferred to the meeting and messages will be placed on the message board. Please check this board in the Ramo Auditorium lobby for messages.

BADGES: Please return badge holders at the end of the meeting. Deposit boxes will be placed at convenient locations.

1. RAMO AUDITORIUM

2. BAXTER LECTURE HALL

3. BECKMAN LABS LOWER LEVEL '

1. Ramo Auditorium 2. Baxter Lecture Hall 3. Beckman Laboratories 4. Alumni House

HEETING LOCATIONS

2

4. ALUMNI I HOUSE L (SOCIAL HOUR} L

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WEDNESDAY# June 191 7:30 a.ft.

25th FLAT-PLATE SOLAR ARRAY PROJECT INTEGRATION HEETING

7:30 a.ft. Registration in Lobby of RaRo AuditoriuR. California Institute of Technology

8:30 AnnounceRents and FSA Overview Ra"o AuditoriuR ij. Callaghan (JPL) 10 Rin.

8:40

9:00

DOE CoR"ents

SURRary of Solar Cell High-Efficiency Research Results

9:25 Overview of Processing Activities Directed Toward Higher-Efficiency# Large-Areal Crystalline-Silicon Solar Cells and Hodules That Would be Econo"ical To Produce

9:50 BREAK

10:20

10:40

11:0D

SuRRary of Process Research Analfsis Efforts for Higher-Efficiency Crystall1ne-s1 icon Solar Cells; AccoP1plish~ents1 Potentials and LiPlitations

SUPlftary of Hetallo-Organic Process Technology Efforts Leading to H1gner-Eff1c1ency Crystalline­Silicon Solar Cells; AccoRplishftentsl Potentials and LiRitations

SuRRary of Directed Energy Process Technology Efforts Leading to A1gher-Ett1c1ency Crystalline­Silicon Solar Cells; Accoftplish"ents. Potentials and LiRitations

Research foruft Suftftaries

11:20 Crystal Growth for High-Efficiency Silicon Solar Cells

11:40 Reliability and Engineering of Thin-FilR Photovoltaic Nodules

12:00 LUNCH

1:15 Parallel Technology Sessions Advanced Silicon Sheet Nodule Develop~ent & Engineering Sciences Process DevelopAent

5:15 SOCIAL HOUR

THURSDAY, June 20

8:00 a.R. Parallel Technology Sessions High-Efficiency Device Research Reliability Physics Silicon Haterial and JPL Web Teaft

12:0D LUNCH

1:30 p.ft. Future Directions Late News

3:00 BREAK

3:20 Suftftaries

4:20 End of neeting

Ra"o Auditoriu11 Baxter Leet. Hall Beck,.an Labs.

Aluftni House

Ra1110 Auditoriu,a Baxter Leet. Hall Beckftan Labs.

Rafto AuditoriuPI

H. Prince (DOE) 20 ftin.

R. Kachare (JPL) 25 Plin.

D. Bickler (JPL) 25 Rin.

D. Burger (JPL}

30 Rin.

20 fllin.

B. Gallagher (JPL) 20 ftin.

P. Alexander (JPL) 20 Plin.

K. Du,1as (JPL)

E. Royal (JPL)

A. Briglio (JPL) H. Sftokler (JPL) D. Bickler {JPL)

D. Burger (JPL) R. Ross (JPL) R. Lutwack (JPL)

20 Rin.

20 flin.

4 hrs. 4 hrs; 4 hrs.

4 hrs. 4 hrs. 4 hrs.

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ADVANCED SILICON SHEET

Wednesday, June 19 1:15 p.m. (Ramo Auditorium)

1:15 Silicon Ribbon Stress/Strain Workshop

1:30 Silicon Dendritic Web Ribbon Process

2:10 Defect Characterization of Silicon Dendritic Web Ribbon

2:25 Characterization of Silicon Sheet

2:40 Analysis of Stress/Strain Relationships

3:00 BREAK

3:20 Stress Studies in Edge-Defined Film-Fed erowth of Silicon Ribbons

3:40 Low-Angle Silicon-Sheet Growth

4:05 Analysis of High-Speed Growth of Silicon Sheet in Inclined-Meniscus Configuration

4:25 Optimization of Silicon Crystals for High-Efficiency Solar Cells

4:45 Silicon Sheet Surface Studies

5:00 Discussion

4

A. Briglio, Chairman

M. Leipold (JPL)

15 min.

R. Hopkins 40 min. (Westinghouse Electric co.)

L.J. Cheng 15 min. (JPL)

S. Hyland 15 min. (Cornell Univ.)

O. Dillon 20 min. (Univ. of Kentucky)

20 min.

J. Kalejs 20 min. (Mobil Solar Energy Corp.)

J. Milstein 25 min. (Energy Materials Corp.)

R. Brown 20 min. (Massachusetts Inst. of Tech.)

T. Ciszek (SERI)

20 min.

S. Oanyluk 15 min. (Univ. of Illinois at Chicago)

15 min.

n MODULE DEVELOPMENT AND ENGINEERING SCIENCES

Wednesday, June 19, 1: 15 p. m. (Baxter Lecture Hall)

1:15 High-Efficiency Nodule Design

1:45 Flanmability Research

2:05 Bypass-Diode Qualification Testing

2:25 Development of AM1.5 Global Measurement Procedures and International Cell Measurement Round Robin

2:55 BREAK

3:25 Amorphous-Silicon Cell Reliability Testing

3:55 Photocurrent Images of Amorphous-Silicon Modules

H. Smokler, Chairman

M. Spitzer 30 min. (Spire Corp.)

R. Sugimura 20 min. (JPL)

D. Otth 20 min. (JPL)

R. Mueller 30 min. (JPL)

30 min.

J. Lathrop 30 min. (Clemson Univ.)

Q. Kim 20 min. (JPL)

4:15 Amorphous-Silicon Module Hot-Spot Testing C. Gonzalez . (JPL)

30 min .

4:45 Photovoltaic-Array Design Options

5

D. Burger (JPL)

20 min.

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PROCESS DEVELOPMENT

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Wednesday, June 19, 1:15 p.m. (Beckman Laboratories)

1:15 Introduction

1:20 Laser-Assisted Processing

1:50 Laser-Assisted Processing

2:10 Amorphous Metals

2:30 BREAK and POSTER SESSION*

3:00 Ink-Jet Printer and HOD Metallization

3:20 Laser-Assisted Junction Formation

3:40 Laser-Assisted Metallization

4:00 Microwave-Enhanced Thin-Film Deposition

4:10 Life-Cycle Costs of High-Performance Cells

4:30 SAMICS on the IBM PC

4:50 Encapsulation Processing

[J *POSTER SESSION (JPL Activities)

Amorphous Silicon Deposition Effort

Parametric Sensitivity Studies

6

D. Bickler, Chairman

D. Bickler 5 min. (JPL)

0. Wong 30 min. (ARCO Solar, Inc.}

A. Greenwald 20 min. (Spire Corp.)

M.-A. Nicolet 20 min. (Calif. Inst. of Tech.)

30 min.

R. Vest 20 min. (Purdue Research Foundation)

R. Campbell 20 min. (Westinghouse Electric Corp.)

A. Rohatgi 20 min. (Westinghouse Electric Corp.)

S. Chitre 10 min. (Superwave Tech. Inc.)

R. Daniel (JPL)

R. Chamberlain (JPL)

20 min.

20 min.

P. Willis 20 min. (Springborn Laboratory)

D. Bickler (JPL)

E. Lin (JPL)

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HIGH-EFFICIENCY DEVICE RESEARCH

Thursday, June 20, 8:00 a.m. (Ramo Auditorium)

8:00 Heavy-Doping Considerations and Measurements in High-Efficiency Cells

8:20 Measurements of Recombination Parameters in Solar Cells

8:40 Measurements of Properties of Heavily­Doped Silicon

D. Burger, Chairman

F. Lindholm 20 min. (Univ. of Florida)

M. Wolf 20 min. (Univ. of Pennsylvania)

R. Swanson (Stanford Univ.)

20 min.

9:00 Measurements of Silicon Surface-Interface _C. Bates, Jr. 20 min. Properties (Stanford Univ. )

9:20 Role of Oxygen and Carbon in Silicon Solar Cells

9:40 Comprehensive Solar Cell Modeling and Correlation Studies

10:00 BREAK

10:15 Loss Mechanisms in High-Efficiency Solar Cells

10:35 Fabrication of High-Efficiency Cells Based on Novel Structure

10: 50 SiNx Layers and MINP Solar Cells

11:10 High-Efficiency Solar Cells Fabrication and Bulk-Loss Reduction

11:30 Bulk-Loss Reduction Concepts

11:45 Surface and Bulk-Loss Reduction Research by Low-Energy Hydrogen Doping

1

J. Corbett 20 min. (State Univ. of NV, Albany)

M.L. Lamorte 20 min. (Research Triangle Inst.)

15 min.

C.T. Sah 20 min. (C.T. Sah Associates)

F. Ho 15 min. (Applied Solar Energy Corp.)

L. Olsen 20 min. (Univ. of Washington, JCGS)

A. Rohatgi 20 min. (Westinghouse Electric Corp.)

6. Rozgonyi 15 min. (North Carolina State Univ.)

S. Fonash 15 min. (Pennsylvania State Univ.)

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RELIABILITY PHYSICS

Thursday, June 20, 8:00 a.m. (Baxter Lecture Hall)

6:00 Photothermal Degradation

8:20 Photodegradation Hodeling

B:40 Polymeric UV Stabilizers and Absorbers

9:00 PV Module Interface - General Purpose Primers

9:15 Encapsulation Materials Research

9:45 BREAK

10:05 Moisture-Conductivity Dependencies in Module Encapsulants

10:35 Moisture-Sorption Dynamics in Module Encapsulants

10:55 Electrochemical Research

11:25 Theoretical Validation of (RH+ T) Weathering Correlation

11:45 Discussion

8

R. Ross, Chairman

R. Liang 20 min. (JPL)

J. Guillet 20 min. (Univ. of Toronto)

O. Vogl 20 min. (Polytechnic Inst. of NV)

J. Boerio 15 min. (Univ. of Cincinnati)

P. Willis 30 min. (Springborn Laboratories)

20 min.

G. Mon 30 min. (JPL)

L. Wen 20 min. (JPL)

J. Orehotsky 30 min. (Wilkes College)

E. Cuddihy 20 min. {JPL)

15 min.

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SILICON MATERIAL AND JPL WEB TEAM

Thursday, June 20, 8: 20 a. m. (Beckman Laboratories)

8:20 Silane Process Research and Development

R. Lutwack, Chairman

S. Iya 20 min. (Union Carbide Corp.)

8:40 Modeling of Fluidized-Bed Reactors P. Ramachandran 20 min. for the Deposition of Silicon from Silane (Washington Univ., St. Louis)

9:00 Fluidized-Bed Reactor Research

9:20 Silicon-Particle Growth Research

9:40 Discussion

10:00 BREAK

JPL WEB TEAM

10:30 Introduction

10:35 Thermal Analysis

11:05 Stress Analysis and Material Properties

11:25 Discussion

9

G. Hsu (JPL)

20 min.

R. Flagan 20 min. (Calif. Inst. of Tech.)

30 min.

R. McDonald 5 min. (JPL)

R. Richter 30 min. (JPL)

B. Wada 20 min. (JPL)

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TECHNICAL SUMMARIES:

In-House Summaries

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In-House Program

Amorphous Metals

Jet Propulsion Laboratory Pasadena, CA 91109

The stability of sputtered W-N alloys as diffusion barriers in Si metallization schemes was studied. The composition of W-N barriers is varied over a wide range including pure W •. The range of nitrogen par­tial pressures from 15 to 35% in the sputtering atmosphere yields amor­phous W-N alloys of composition W100-xNx, x 20-35. Sputtered metal films of Ag, Au or Al are used as low resistivity overlayers. Metal­lurgical interactions at temperatures ranging from 500°C to 900°C are studied using RBS for atomic depth profiles, sheet resistance measure­ments for electrical stability, and optical microscopy as well as SEM for the analysis of localized failures. X-ray diffraction was used to obtain structural information on the W-N alloys.

Incorporating N into W advantageously stabilizes the systems with all three metal overlayers. The overall failure takes place rapidly above a critical temperature of the barrier. In particular, it was found that amorphous W-N alloy are exceptionally effective diffusion barriers for Au up to 800°C.

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In-House Program

AMORPHOUS SILICON DEPOSITION

Jet Propulsion 'Laboratory Pasadena, California

The objective of this task is to generate generic data for the design of deposition chambers, and to develop large area deposition systems that will assist in the verification of DOE-funded processes and the transfer of this technology to industry.

The previously reported one dimensional (varying only in the direc­tion perpendicular to the large parallel electrodes) aspect of the RF plasma has stood the test of time. Experiments have shown that at an unconfined electrode edge, the plasma spreads out, creating an expan­ding central zone (the positive column). This zone is prone to pro­duce the excessive silane polymerzation which results in the "dust" formation. Poor deposition quality has been found to corrolate with the formation of this dust. Confining the edge of the elctrodes pre­vents this spreading out of the plasma layers.

The rapid diffusion of silane in hydrogen has been both calculated and demonstrated. The exploitation of this mass transport mechanism requires a mathematical model in order to optimize process conditions. By developing such a model as well as other models to address plasma geometry, silane utilization, deposition rate, and conditions of pres­sure and temperature, it is expected that generic engineering level information will.evolve which is applicable to RF plasma systems in general.

Complete devices (glass-ITO-p-i-n-metal) have been fabricated by con­ventional patterning and overlaping layer design. Due to shunting through numerous pin holes, the power generating capability was nil.

A new chamber configuration has been built. The heated electrodes are dielectrically isolated with pyrex plates. The nozzles (silane en­trance and exit) and the metallic side walls are electrically grounded. The RF high voltage transformer has a grounded center tap which forces electrical symetry upon the electrodes. The results in identical depo­sitions on both electrodes simultaneously.

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ADVANCED SILICON SHEET TASK

Jet Propulsion Laboratory Pasadena, CA 91109

In-House Program Characterization of Silicon Sheet Material

Two programs are described herein, one on high-temperature silicon mechanical properties and the other on fracture mechanics of silicon sheet.

The purpose of the effort on high-temperature silicon mechanical properties is to determine these properties in order to refine ribbon stress/strain models and to characterize the response of the material. A Centorr Inc. high-temperature inert-gas (vacuum-compatible) furnace and controller was integrated into existing mechanical test equipment. This furnace was used along with a closed-loop hydraulic test machine to perform uniaxial tensile tests on silicon sheet material from 800°C to 1350°C.

Initial testing was difficult due to premature fracture of silicon sam­ples and test equipment problems such as shorting of heater elements and test chamber overheating. These problems have been overcome. Czochralski (Cz) wafers abrasively cut into "dog bone" configurations were used for most samples to date. Flow stresses from 2 KSI down to 0.2 KS! were recorded over the temperature range of 800°C to I350°C for Cz material. Also, upper and lower yield phenomena were observed. The first sucessful high-temperature pull tests on Westinghouse silicon dendritic web material were completed. Flow stress values similar to Cz material were obtained. Physical/microstructural features, such as thickness, surface profiles, X-ray topographic structure, and residual stress of terminated web and "buckled" Mobil edge-defined film-fed growth (EFG) material, were documented.

The JPL in-house effort on fracture mechanics of silicon is directed toward evaluating crack propagation in silicon under the influence of fluid environment. Single-crystal wafer specimens were pre-cracked in the <111) plane and loaded in the double-torsion configuration. The crack propagation rate along the <Ill) cleavage plane at room tempera­ture in air was measured as baseline data. The preliminary results indicated that crack propagation by jumping was found at the critical stress intensity factor. Also a sample cracked by double torsion was evaluated by X-ray topography. A small residual, plastic strain field was observed by this technique. These efforts are directed at under­standing the interaction of dislocations (or plastic zone efforts) and crack propagation in silicon as a function of room-temperature environments.

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In-House Program

DEVICE RESEARCH TASK

Jet Propulsion Laboratory Pasadena, CA 91109

Defect Characterization of Silicon Dendritic Web Ribbons

A study on properties and distributions of structural defects in sili­con dendritic web ribbons is being conducted. The techniques used to reveal structural defects are chemical etching combined with optical microscopy. The electron beam induced current (EBIC) technique is used to examine the recombination activities of the defects.

A simple analysis of the distribution of etch pits due to slip dislo­cations shows the existence of two distinguishable stress regions in the ribbon during the plastic deformation stage, namely, shear stress at the ribbon edges and tensile stress at the middle. Some estimates of stress based on the etch pit densities along the aligned dislocation patterns were done. The results indicate that the shear stress near the edge can be as high as about 108 dynes/ cm2, which is consistent with the theoretical analysis of thermal stress distribution by West­inghouse and JPL. The high dislocation density is often found at the junction of the dendrite and the ribbon, about 1 to 1. 5 mm from the edges of the ribbon. Additional broad maxima of dislocation density due to shear stress are often observed in the sample (about 3 to 6 mm from the edge).

Recombination activities of two slip dislocations in the ribbon were examined using EBIC. The activities vary with the complexity of the defect. For example, simple slip dislocations cannot be observed using EBIC at room temperature, but they can be seen at temperatures below 200K. Dislocation complexes have stronger recombination activities and can be seen at room temperature.

EBIC experiments were carried out on the cross sections of the ribbon. The results show that the twin plane of the ribbon is often decorated with high-concentration, discrete structural defects that are recombination-active at room temperature. In addition, the cross­section EBIC results also reveal the existence of other structural defects in the ribbon, which are recombination-active at room tempera­ture. A preliminary result indicates that the density of these defects is approximately zero in the material adjacent to the ribbon surface. The existence of a .. defect-free" region under the surface could be related to the growth condition.

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DEVICES AND MEASUREMENTS RESEARCH TASK

In-House Program

Significant progress in cell fabrication research has been made during past six months. Silicon solar cells of efficiencies up to 17. 4% at AMI. 5 (measured at SERI) were fabricated using O. 2 ohm-cm, (100), 300 µm thick wafers with 0.23 µm phosphorus-diffused junction depth. Ti02/ Alz03 films of 500/ 1100A thickness were used as anti reflection coating with no fassivating oxide. The best performance characteris­tics of 4 x 2 cm cells are V

0c = 640 mV, I

8c = 270 mA, and FF= Q.806.

Research activities on cells with equidiameter dot junctions evenly distributed across the surface for reduction of the saturation current and increase in open circuit voltage have continued. A theoretical analysis suggests that the cell design is capable of achieving effi­ciencies reaching 20% for one sun illumination. Experimental results show a gradual reduction in the saturation current as the junction area is reduced.

The performance of an innovative high-efficiency silicon solar cell design has been theoretically investigated. The design utilizes sili­con oxide passivation at the front and back surfaces, heavily-doped polycrystalline silicon layers under the metal contact for surface passivation under contact, and back surface reflection for efficient usage of sunlight. The results indicate that a silicon solar cell of 20% efficiency is practically achievable using this design with front and back surface recombination velocities being 1000 cm/sec and bulk minority carrier lifetime of 20 µs.

EBIC experiments were carried out on the cross sections of silicon den­dritic web ribbons. The results show that the twin plane of as-grown ribbon is often decorated with high-concentration, discrete structural defects which are recombination-active at room temperature. An experi­ment has been carried out with the objective of examining the effect of phosphorus diffusion on the recombination activities of these struc­tural defects. Preliminary results indicate that phosphorus diffusion can reduce their activities, but cannot completely eliminate them.

A minority-carrier lifetime measuring system using a microwave bridge technique has been assembled. Preliminary results show that the system is capable of monitoring photoconductive decay of silicon with resis­tivities down to about 0.1 ohm-cm.

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In-House Program

RELIABILITY AND ENGINEERING SCIENCES AREA

Jet Propulsion Laboratory Pasadena, California

Module and Array Engineering Sciences

Module Flammability Research

Research continued in an effort to increase flammability resistance of photovoltaic modules with hydrocarbon encapsulants (EVA, PVB, etc.) through the use of improved module construction techniques and new high-temperature, back-surface materials. At the last PIM, several materials were identified as candidates for satisfying Class B fire-resistance requirements. Since that time additional tests have focused on materials and constructions that satisfy Class A fire­resistance requirements.

The starting point was Refrasil, an expensive, fiberglass cloth consisting of 97% silica, currently used in shipbuilding as protection against weld splatter. Refrasil, when coated with Z-mix, a proprietary high-temperature coating, successfully passed the Class A burning-brand test at Underwriters Laboratories, Inc. during tests in Oct. 23-24, 1984. Subsequent tests, performed during Mar. 12-14, 1985, indicate that less expensive glass cloths impregnated with Z-mix are also capable of passing the Class A burning-brand test. Additionally, the test results indicate that the edges of the module have minimal fire resistance.

The next series of fire tests, scheduled for May 21-25, 1985, is expected to include tests of advanced module edge seal designs using high-temperature materials. Solarex Corp. will join ARCO Solar, Inc. and Solavolt International in participating in this collaborative research effort.

Much of this work has been summarized in a technical paper entitled, "Development and Testing of Advanced Fire-Resistant Photovoltaic Modules" by R.S. Sugimura, D.H. Otth, and R.G. Ross, Jr., and presented at the 31st Annual Meeting of the Institute of Environmental Sciences in April 1985 •

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In-House Program

RELIABILITY AND ENGINEERING SCIENCES AREA

Jet Propulsion Laboratory Pasadena, California

Module Performance and Failure Analysis

The Block V module development program has been completed, following successful qualification testing of the modules of all five contrac­tors. The design and performance of these modules is described in the User Handbook for Block V Silicon Solar Cell Modules, JPL Document No. 5101-262, DOE/JPL-1012-106, dated May 15, 1985, which is now being printed.

Environmental testing of modules has been performed on a sampling of coDDnercial U.S. and foreign crystalline-silicon-cell modules. The opportunity to obtain and test these modules has shown that many features of the Block V technology, including tempered-glass superstrate, laminated construction, EVA encapsulant, plastic film or laminate back cover, and fault-tolerant interconnect and circuitry designs, have been adopted internationally and that the resultant modules are behaving well under test.

As part of the electrical measurements ac·tivities a design modification has been made to the LAPSS so that the resultant irradiance spectrum closely simulates that of the ASTM AM1.5 Global Spectrum defined in ASTM E 892-82. Therefore, we can now perform module measurement and secondary calibration of reference cells without the need for a reference cell that exhibits a close spectral match to the response of the subject module or cell. We already have the same capability, because of a former LAPSS modification,relative to the ASTM AM1.5 Direct Normal Spectrm in ASTM E 891-82.

Several "pseudo-amorphous" reference cells have been constructed and calibrated. They consist of crystalline silicon cells of wide spec­tral response combined with an optical filter such that the resultant spectral response is characteristic of amorphous-silicon cells.

The JPL measurement phase of the round robin of reference Qell measurements being conducted by the Commission of European Communities has been completed. The 18 cells in the experiment, which include single crystal, semi-crystal and amorphous cells fabricated by five countries, have been shipped to Japan, the last country to perform the measurements before the cells return to the CEC Joint Research Centre, Ispra, Italy, for final measurement and for initiation of the data analysis phase of the round robin. Four of the 18 cells were provided by JPL.

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In-House Program

In the failure analysis effort several analyses have been performed of modules that exhibited anomalies in JPL environmental tests and in various field installations. Other activity has included the modification of the Solar Cell Laser Scanner to permit selection of laser wavelength, principally for application to analysis of defects in amorphous silicon submodules.

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PROJECT ANALYSIS AND INTEGRATION

Jet Propulsion Laboratory

Pasadena, California

PVARRAY, A SOF'IWARE TOOL FOR PHOTOVOLTAIC ARRAY DESIGN

Optimizing the performance of a photovoltaic (PV) array requires consideration of a number of design factors and the resultant system interactions. The design factors involved can include: series­parallel wiring of modules and array, module size, cell I-V curve, diode cost and placement, and failure rate and replacement philosophy. PVARRAY simulates array performance with selected variations of the design factors.

PVARRAY is a computer program that simulates the power output of an array of PV modules over its lifetime. There are three major modules in PVARRAY: PVMAIN for data input; PVPERF, which takes the input data and assigns random cell failures in different time intervals, and simulates the array I-V curves and system performance; and PVCD, which calculates array performance when each cell has a built-in diode.

PVARRAY is capable of simulating a wide variety of module and array configurations. At this time, a total of 120 simulations have been performed. Results indicate that higher parallel redundancy is favored as is increasing diode protection. Replacement strategy is only of moderate interest since a well protected module rarely needs replacement. High-efficiency cells make the array performance more sensitive to failures. These results, which will be summarized at the twenty-fifth PIM, are consistent with previous parametric studies.

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In-House Program

LIFE CYCLE COST AND PERFORMANCE COMPARISONS OF PHOTOVOLTAIC TECHNOLOGIES

After the initial cost of purchase and installation of a photovoltaic (PV) system the user expects many years of generated power with minimal maintenance and module replacement due to failures. The real value of a PV system must include all costs and revenues associated with the system over its lifetime. A study is in progress that will determine the value of improvements to the lifetime power output of a system and how much additional expense can be added during cell and module fabrication to acquire added performance. The study compares the net present value of several PV module production technologies, including current state-of-the-art and future high efficiency cell technologies. Preliminary results of the study will be described at the twenty-fifth PIM.

The following three simulation models developed at JPL were used for the analysis: PVARRAY, which simulates array performance over time; SAMICS (Solar Array Manufacturing Industry Costing Standards) which estimates the process value added and the manufactured module cost; and, LCP (Lifetime Cost and Performance) which calculates hourly energy over time, pre-tax revenue from the system, and nominal cost streams over time. All of these programs can be run on an IBM XT or compatible personal computer.

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In-House Program

SENSITIVITY STUDY OF PV PROGRAM GOAL PARAMETERS

The scope of the PV system sensitivity has been broadened to include parameters not reported previously. Energy cost sensitivities and/or allowable module cost/efficiency calculations have been performed for the following parameters: module cost and efficiency, tracking configuration, balance of system (BOS) efficiency, area-related BOS costs, power related BOS costs, indirect costs, insolation, the fixed charge rate, and the energy cost goal.

Some results of the study are (1) module cost and efficiency are the two most critical technical components of system energy cost. Not only is a large portion of life-cycle energy cost related to these items, but they also exhibit the greatest potential for improvements through research. (2) Generally, one-axjs tracking offers lower energy cost than fixed-or two-axis configurations. (3) Because of the enormous influence of the energy cost goal on allowable module costs, the future of PV depends on the changing economic status of competing generation technologies as much as it depends on R&D progress in PV technology.

ENERGY COST

Energy cost calculations were made for residual fuel oil based on the same energy cost methodology used by DOE for the PV Program, and on data contained in the EPRI Technical Assessment Guide. Results of the analysis indicate that $0.20/kWh is competitive with residual oil-fired generation. At 20i/kWh, realistic module costs and efficiencies can be achieved and PV can begin to penetrate central station electricity generation.

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GRID OPTIMIZATION

Two reports have been written. (1) "Documentation of CELLOPT: A grid Optimization Design Program" describes how to use CELLOPT. CELLOPT assists in the design of an optimal collection grid on round or rectangular solar cells. (2) "Documentation of TCMLOSS: Optical and Electrical Losses in a TCM", describes how to use TCMLOSS. The TCMLOSS program helps analyze and calculate the optical and electri­cal losses associated with using a TCM on a solar cell. After using TCMLOSS to select the TCM with the best characteristics, CELLOPT can be used to describe the optimal grid pattern to be used on the TCM coated solar cell.

SAMIS: A PV FACTORY IN A PC

SAMIS now runs on a PC. SAMIS, which is an acronym for the Standard Assembly-line Manufacturing Industry Simulation computer program, is the analytical heart of SAMICS, the Solar Array Manufacturing Industry Costing Standards. The later has been used by the Flat­Plate Solar Array Project at JPL to compare prospective manufacturing processes and process sequences in terms of the prices that would have to be received for the final product to recover all costs and make a specified profit. SAMICS also includes standardized prices of inputs (the Cost Account Catalog), standardized formats for describing processes, and the !PEG (acronym for Improved Price Estimation Guidelines) method for assessing sensitivities.

SAM IS has been rewritten in Turbo-Pa sea 1. Previously, it was written in Simscript and available only on a mainframe computer. The interface between the program and the user has been completely redesigned. Before, the user had to learn a vocabulary of SAMIS connnands. Now, all choices are displayed and fully explained; even a User's Manual is scarcely needed. The SAMIS data management procedures provide a full-screen editing capability with the feel, and ease of use, of a spread sheet.

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The algorithm for allocation of indirect requirements, which are computed at the company's scale of operation, has been significantly improved. And, the Cost Account Catalog, which contains price versus quantity relationships and inflation rate tables for all items pur­chased outside the hypothetical factory, has been thoroughly updated. SAMIS Release 6, which will soon be available, will be described at the PIM.

SIMRAND UPDATE

A newly developed. random number generator has been incorporated in the FORTRAN ANSI-77 version of SIMRAND. The program is able to duplicate the results of the earlier versions. SIMRAND (SIMulation of Research ANd Development Projects) is a general methodology that cal~ulates a-;easure of performance for any R&D project having a number of systems or tasks that can be quantified in terms of proh­abilistic variables. The methodology models R&D projects as network of tasks. SIMRAND I (no network search) has been used to estimate the price of producing silicon solar cell modules. SIMRAND II, which is now in progress, will build upon the methodology of SIMRAND I by incorporating a network search and optimization methodology.

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RELIABILITY AND ENGINEERING SCIENCES AREA

Jet Propulsion Laboratory Pasadena, California

Reliability Physics

Electrochemical Corrosion Research

Equilibrium cell to frame leakage currents of encapsulated photo­voltaic test coupons have been measured at 400c, 550c, 700c, and s5oc with relative humidities varying at each temperature from about 40% to 100%. Test variables included electrode polarity, electrode spacing, and encapsulant type, the two under consideration being PVB and EVA. This data will enhance photovoltaic array field life prediction capability in addition to understanding of module response to transient environmental temperature/humidity variations •

Module tests at 850C/85% RH have also been conducted in a fashion similar to that of the JPL Block V Qualification test, but with 500 volts DC impressed between cells and frame.

Recent findings include the observations that: degradation for the two polarities have different characteristics but proceed at approximately the same rate; EVA is three orders of magnitude more resistive than PVB; a correlation between laboratory chamber test ti.me and field environment exposure time has been developed.

Recent tests on amorphous silicon modules have been completed. They indicate that corrosion rates are of about the same order of magnitude as for crystalline silicon modules.

Water-Module Interaction Research

A program to measure the electrical conductivity, as a function of temperature and water content, of photovoltaic module components, such as encapsulants and substrate films, is in progress. The moisture sorption of PVB, EVA, and Tedlar, and combinations of these, are measured at various temperature/Relative Humidity levels. Also, the electrical conductivity of identical samples is measured for the same T/RH levels •

Recent testing of specially prepared samples are revealing the paths of leakage current conduction in photovoltaic modules. The conduction is generally along interfaces or on free surfaces rather than through the material bulk.

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Reliability/Durability of Electrical Insulation

Recent work in this area consists of periodically monitoring partial discharge inception voltage levels and pulse height analysis profiles of all samples undergoing long-term electrochemical testing. This data reveals the propensity of samples to break down electrically under increasing exposure to environmental stresses.

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RELIABILITY AND ENr,JNEERING SCIENCES AREA

Jet Propulsion Laboratory Pasadena, California

Reliability Physics

Photothermal Stability Research

EVA samples have been photoirradiated at various temperatures to eval­uate the rate of photo-induced bleaching. Aging studies have been completed at low temperatures. It was found that the photo-induced bleaching rate was substantial at a low temperature of 50°C. Higher temperatures of 120°C and 135°C and intensities of 1 sun each were evaluated next. A steady-state condition with yellowing~. 1 .25 x 10- 2

absorbance units was achieved. It was found to be considerably less than yellowing achieved from previous studies of aging at 120°C, 6 suns and at a much slower rate.

Work was initiated on samples which will be aged at 120°C, 2 suns intensity and 120°C, O sun intensity {dark oven) in order to get an overall picture of EVA photothermal aging. These results will be incorporated into an analytical model which can be used to predict yellowing behavior of EVA.

Polytechnic Institute of New York, Brooklyn, is continuing its work on the synthesis of efficient UV stabilizers that can be incorporated as permanent stabilizers into condensation and addition type polymers. Incorporation into polyesters and polycarbonates has been completed. Characterization of these incorporations are continuing.

Reliability/Durability of Bonded Materials

Monitoring of interfaces for fundamental information related to chem­ical debonding mechanisms and aging kinetics for assessing bond life potential is continuing. In order to spectroscopically examine the chemical bonded interphase between EVA and glass it was determined that the EVA-glass primer system required water as a chemical ingred­ient. Isotropic water was used in place of normal water so that distinct IR frequencies would be produced from the silicon-oxygen bond on the glass surface and the "silicon-oxygen" bonds within the glass bulk. Springborn Laboratories have prepared the glass/EVA primer with isotopic water for a feasibility experimental effort by Dr. Koenig at Case Western Reserve University. These studies are now in progress.

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SILICON MATERIALS TASK

Jet Propulsion Laboratory Pasadena, California

Silicon Materials Processing Research

A study was continued to establish the process and basic mechanism for deposition of silicon from the decomposition of silane onto particles in a fluidized-bed reactor (FBR) and to characterize the purity of silicon seed particles and product.

Initial purity experiments were conducted using a quartz liner in the FBR and silicon seed of 200-micron diameter prepared in a fluid jet mill. Neutron activation analysis indicated metallic impurities in the ppma range. To eliminate this problem, a seed cleaning system employing an FBR was designed and built. The silicon cleaning proce­dure consists of six steps: (1) washing with deionized water, (2) cleaning with a mixture of two parts of 12N HCl and one part of 16N HN03 for 20 minutes, (3) washing with deionized water, (4) etching with 48% HF for 20 minutes, (5) washing with deionized water to the point that the effluent water resistivity is 16 megohms, and (6) drying in a diffusion furnace at 150°C under nitrogen environment. All washing and cleaning procedures were conducted in the fluidized-bed mode to ensure good mixing. The silicon particles prepared by this procedure have a total metallic impurity content of less than 100 ppba. Work is under way to conduct product purity FBR experiments using these clean silicon particles. ·

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TECHNICAL SUMMARIES:

Contractor Summaries

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FSA Applied Solar Energy Gorp. and University of Illinois

City of Industry, ,_ .. .,_

Contract Title:

Contract No.:

OBJECTIVE

Apply state of art technologies to develop novel PV cell, to achieve AMl.5-one-sun efficiency above 20% at 28°C. Cell design based on Dr. Sah's model.

TASKS

(1) Define critical parameters (Sah/ ASEC). (2) Design and fabricate test patterns to (ASEC/Sah). Explore model. (3) Fabricate cells based on results in (2). (4) Fabricate 4 cells above 20%.

PROGRESS (SECOND MONTH)

Evaluating P-type and N-type silicon· ingots by proof-tests using "conventional" high efficiency cell technology. Select slices for test pattern study. Designed ma.sks with test patterns. Delivery in May.

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Contract Title:

Contract No.:

CELL PROCESSDG ARD HIGH EFFICIDCY CELLS AB.CO SOLAR, IBC.

CBATSWOR'l'B, CA

Pulsed Excimer Laser Processing for Cost-Effective Solar Cells

956831

The objective of this contract is to develop a solar cell process sequence that incorporates up to three process steps which use pulsed excimer lasers, to verify that this sequence yields high efficiency cells at a potentially low cost, and to document the feasibility of carrying this technology from the laboratory bench scale to factory size. The three process steps are: junction formation, surface passivation, and front metallization. The effort is to take place during a one-year period.

A series of experiments has been conducted toward developing a process for optimum junction formation on large area solar cells. Parametric variations included beam energy density, percentage of beam overlap, sources of dopant, and various surface preparation conditions such as chemical-mechanical polished (CMP), caustic etched, and textured. Diffusant deposition included spin-on liquid dopant and ion implant. Experimental results indicate that the most important factors in obtaining ideal junctions are laser uniformity and surface condition. The requisite of near-perfect surface condition for optimum results rules out all other surface finishes and methods of dopant deposition except CMP with low energy ion implant. Parameters for surface cleaning, ion implant, laser energy density, and overlap percentage to obtain the shallow junction have now been finalized, and proven to produce cell efficiencies at or above 15.8%.

Equipment for CVD gridline metal deposition has been completed and tested. The three major areas to be evaluated are adhesion, deposition rate, and plate-up processing. The same equipment configuration except for reactant gases is used for oxide deposition. Results and recommendations will be presented.

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Contra ct No.:

ENGINEERING SCIENCES AREA

Clemson University Clemson, SC 29631

INVESTIGATION OF ACCELERATED STRESS FACTORS AND FAILURE/DEGRADATION MECHANISMS IN TERRESTRIAL SOLAR CELLS

954929

The goal of this research program is to be able to identify, through laboratory accelerated testing methods, fundamental physical, chemical, and metallurgical phenomena which cause solar ·cells to degrade with time. Historically the program has concentrated on crystalline silicon cells, both unencapsulated and unencapsulated, but effort is now shifting to thin film cells. In order to effectively utilize accelerated stress testing, three conditions must be met: 1) samples being stresses must be representative of the manufactured population, 2) a stress "window" must exist, and 3) the measurement methods used must have a sufficient degree of repeatability. During the present reporting period a major portion of the contractual effort has been devoted to meeting these conditions for commercial hydrogenated amorphous silicon (a-Si:H) cells.

Individually adressable unencapsulated a-Si:H test cells have been obtained from one manufacturer which were manufactured at the same time and under the same conditions as conunercial monolithic modules. The only structural difference was that cell-to-cell interconnections did not exist and therefore could not be tested. Subjecting these cells to step-stress testing was able to confirm the existence of a stress window by determining the upper temperature limit for long-term accelerated testing. The key to repeatable measurement is the availability of a stable reference cell, which can be used to adjust the intensity of the solar simulator. A stable simulated "reference cell", which avoided both the effects of lamp spectral changes, which occur with age, and of short-term optical instabilities, which can occur in a-Si:11 cells, was fabricated from optically filtered silicon photodiodes.

Host testing thus far has involved unbiased temperature stress, although some 85/85 and pressure cooker humidity testing was also performed. A program has been initiated to utilize Auger electron microscopy in an effort to determine the cause of the observed degradation.

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CORNELL UNIVERSITY Ithaca, New York

Contract Title: Electrical,Structural and Chemical Characterization of Si Sheet Material

Contract No: 956046

The following work was performed between Sept., 1984 and May,1985:

(i) High Temperature Deformation of Web Silicon

Accurate creep data are required for modelling stress relaxation in silicon ribbons. However, because dislocation glide in Web is restricted by internal twin planes, Web silicon is expected to deform differently at high temperatures from single crystal silicon{!). To study these effects experimental creep tests on Web ribbons were performed at Mobil Solar Energy Corporation in four point bending under constant load conditions. The resulting deflection of the ribbon center was plotted against time. An unusual two-stage behavior was observed. Transmission Electron Microscopy will be performed on this ribbon.

Single crystal silicon shows a five-stage deformation behavior at high temperatures(2). The two steady state levels correspond to deformation due to cross-slip of dislocations and deformation due to dislocation climb as a result of vacancy diffusion. The plastic deformation of Web ribbon silicon will be discussed in terms of this model.

(ii) oxygen Measurements in Web

The mechanical behavior of silicon depends on the oxygen content. The oxygen content of Web silicon is unknown because experimentally it is difficult to ascertain since the ribbons are very thin and the surfaces cause a great deal of reflection. A program to measure the oxygen content of Web ribbons has been started and results obtained to date will be discussed.

1. Gleichmann, R., M.D. Vaudin and D.G. Ast, Phil. Mag. A, 1985, Vol.51, No.J, 449-467.

2. Siethoff, H., Phil. Mag. A, 1984, Vol.50, No.l, Ll-L6.

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Con tract Ti tie:

Contra ct No.:

THrn FILM TESTING TASK Hughes Aircraft Company Long Beach, California

AMORPHOUS SILICON PHOTOVOLTAIC MODULES AND TEST DEVICES BD-802409

The goals of this contract are the design, fabrication and environmental testing of 10 Amorphous Silicon (A-Si) PV modules to JPL Block V specifi­cations. Test results are to be evaluated for potential A-Si submodule and submodule packaging design improvements.

Since last October, six modules have been fabricated and delivered to JPL for testing. Module fabrication efforts were impeded by submodule breakage during lamination. This problem should be eliminated in future lamination efforts by the use of submodules having an improved edge finish.

The proximity of the A-Si circuit to the aluminum module frame has caused difficulty in meeting the 3 KV hipot test requirement. This problem has produced a successful search for laminate edge seals with greatly increased electrical isolation properties. Submodules with improved edge finishes should also help meet the hipot test requirement by the reduction of elec­trical stress points along the laminate edges.

Successful, high-yield fabrication of the remaining test modules is antici­pated, using the superior components presently being procured.

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Contract Tit I e :

Contract No.:

Advanced Materials Research Task Mobil Solar Energy Corporation

Waltham, Massachusetts 02254

Stress and Efficiency Studies in EFG Silicon

956312

The goals of the contract are to define low stress configurations for silicon sheet growth which are consistent with producing high quality material, and to investigate causes of deficiency in solar cell performance of low resistivity silicon. Experimental and theoretical work is in pro­gress aimed at testing a model for predicting sheet residual stress under conditions where plastic deformation is taking place. Dislocations pro­duced in high temperature creep experiments in FZ and CZ silicon are being studied with EBIC and compared to as-grown EFG material defects in order to relate conditions of formation to behavior in limiting bulk material life­time. Carbon, oxygen and dopant impurity (boron and gallium) effects on dislocation behavior are also under investigation.

The bulk diffusion length of the stressed FZ and CZ silicon is limited by point defect recombination to about 15-25 microns in dislocation-free re­gions after the high temperature(> 1200°C) heat treatment and stress application. Increases in dislocation density from 1 x 104 /cm2 to over 1 x 107 /cm2 further decrease the diffusion length to the range 10-15 microns. One-hour anneals at 575°c and 8S0°c produce little increase in diffusion length, at most by a factor of two, while preferential gettering at dislocations is weak. Significant differences in silicon with varying oxygen and carbon levels are not observed. Samples stressed at lower temperatures are being examined.

The stress modeling at Harvard University has been directed toward imple­menting a new scheme for calculating residual stress, which has important implications for understanding of creep and strain relationships to resid­ual stress. Stress analysis for an EFG test system is in progress, and growth of ribbon is being carried out for comparison purposes to attempt to reduce dislocation densities and stress. Effects of horizontal temperature gradients are also being investigated. Although dislocation densities have been reduced by an order of magnitude by going to slower growth (-1 cm/min) configurations (essentially by decreasing the interface gradient), and stress is decreased, these configurations do not appear to be compatible with restoration of high speed growth(~ 3-4 cm/min).

Characterization of EFG material with varying levels of boron dopant in­dicate that higher dopant levels reduce the dislocation density and that as-grown diffusion lengths for gallium are higher than those for boron.

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Contract Title:

Contract No.:

Goals

Flat-Plate Solar Array Purdue Research Foundation

W. Lafayette, IN

MOD Silver Metallization for Photovoltaics

956679

The goal of this project is to determine the applicability of metallo­organic decomposition (MOD) technology to low temperature metallization of solar cells. The technological goal is to produce silver conductors with low sheet resistance and good adhesion to silicon after low temperature firing of screen printed MOD inks. Activities and Accomplishments Silver neodecanoate was shown to be a very good precursor compound for pro­ducing silver films at firing temperatures below 300°c. A mixture of butyl carbitol acetate and neodecanoic acid was shown to be a good screening agent for the silver inks. Inks with no additional inorganic precursor compounds produced films with excellent initial adhesion, but the adhesion began to degrade after a few days. The addition of a small amount of bismuth 2-ethylhexanoate to the silver ink gave films which retained excellent adhes­ion in excess of 50 days (the duration of the test). The bismuth addition also greatly improved the solder leach resistance of the metallization. Solar cells metallized with the MOD inks had high series resistances. The sheet resistances and the cell performances were improved by thennal spiking (e.g. 800°c for 30-60 seconds). Multilayer films (2-5 layers) Blso gave reduced sheet resistances with only a minimum degradation in line definition. Problems The major problem is to find ways to reduce the high series resistance of solar cells metallized with MOD silver inks. The relative contributions of contact resistance and sheet resistance must be determined in order to identify the cause of the problem.

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Flat-Plate Solar Array Purdue Research Foundation

W. Lafayette, IN

Contract Title: Ink Jet Printing of Silver Metallization for Photovoltaics

Contra ct No.: 957031

Goals The goals of this project are to develop inks and a computer controlled ink delivery system which shall deposit a conductive ink on a solar cell in a defined pattern. A drop on demand ink jet print head will be modified and the required peripheral electrical and mechanical equipment developed. Metallo-organic decomposition (MOD) inks are required so there will be no particulates to clog the nozzles. The printer will be integrated with a CAD system so that the electrode pattern can be printed immediately after the design is completed. Activities and Accomplishments The ink jet printing system uses a Siemens Pt80i head which has 12 nozzles (76 µm diameter) arranged in two staggered rows of six. Each nozzle has its own piezoelectric driver, and a droplet is ejected by means of a pressure wave generated by an impulse from the driver. Substrates are mounted on an x-y table which moves in 25 µm steps in response to input pulses. The desired patterns are generated by programming the motion of the table and the firing of the jets. An SCCS-85 microcomputer board was integrated into the system to take operational and circuit pattern data given it by the host computer, process that data, and then provide the proper signals to the head and the table so that the desired pattern was produced on the solar cell. Research on MOD inks demonstrated that silver neodecanoate is a suitable metallo-organic silver compound, but the selection of the proper solvent was found to be critical. As the drop frequency, and hence film thickness, was increased at a constant table speed, good line definition could be maintained only if very high vapor pressure solvents, such as tetrahydrofuran, were used. Earlier studies showed that a bonding agent such as bismuth added as Bi 2-ethylhexanoate, will be required to insure good long term adhesion. Problems A major decision is the selection of a stand alone CAD system that can be interfaced with the ink jet printer so it can be divorced from the host computer. Ink development studies have revealed an instability problem with formulations of Ag neodecanoate, Bi 2-ethylhexanoate and tetra­hydrofuran, which are the ingredients of choice.

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Contract Title:

Contract No.:

Device and Measurements Research Tasks M. F. Lamorte Research Triangle Institute, P. o. Box 12194 Research Triangle Park, NC 27709

High Efficiency Solar Cell Design Modeling

956741

The goal of this project is the development of a silicon solar cell computer simulation program with high simulation accuracy, simultaneously, with reasonable CPU execution time. Correspondingly, a comprehensive set of phenomena submodels are to be included. Simulation capability is to include the ability to study internal phenomena and their effect on terminal charac­teristics.

In photovoltaic solar cell computer modeling applications, simulation accuracy and CPU cost are most often raised as impediments to the cost­effective use of computer modeling in industrial environments. A computer simulation method has been developed that addresses the two problems raised above. The method applies the Van Roosebroeck set of transport equations to each point of a mesh point field through the use of closed-form solutions that are obtained at each of the points. A computer simulation method will be discussed that provides for equivalent simulation accuracy, but that exhibits significantly lower CPU running time per bias point compared to other techniques. Imposing the appropriate boundary conditions on the closed-form solutions results in a set of equations which require simultan­eous solution. This results in obtaining the solution of all constants of integration, from which, in principle, all cell characteristics may be derived. It has been demonstrated that a recursion relat~onship exists between the constants of integration. In addition, phenomena submodels that are used in the simulation program, which reflect the most recent published silicon properties, will also be discussed. These will include the net charge distributions that are required to establish FSF and BSF and the effects of this change distribution on the Fletcher and Boltzmann boundary conditions. Simulation results will be compared with available experimental data obtained from both high and low efficiency cells. Results show that the maximum percent difference between simulation and.experiment ranges from 0.1% to 3.3%. Similar results· have been obtained for tempera­tures in the ranges of 300 K to 420 K.

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Contract Title:

Contract No.:

LOW-COST SOLAR ARRAY PROJECT SOLAREX CORPORATION Rockville, Maryland

Block V Documentation and Solar Cell Modules

956333

The Solarex Block V, phase II, module is a large frameless module designed for installation in a larger panel framework for use in inter­mediate to large size power system arrays. The module is based on a tempered low iron glass superstrate 54. 78 inches long by 3 7. 69 inches wide. The glass is 0.125 inch thick.

The module contains 117 square semicrystalline silicon cells, each one 10 cm on a side, arranged in a 13 series by 9 parallel matrix, connected by buses at the ends. There are no additional parallel interconnections and no internal diodes. The design peak power at 2soc is the 135-140 watt range.

The module is laminated with two 0.018 inch thick sheets of EVA (Springborn formulation A9918) and features a novel backing comprised of a laminate of Tedlar, Mylar and a modified polyethylene.

The Solarex Block V, phase II, module, designated Model C-120-lOA, has passed the JPL Block V qualification tests.

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April 24, 1985 Date

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MODULE PERFORMANCE AND FAILURE ANALYSIS AREA Spire Corporation

Contract Ti tie:

Contract No.:

Bedford, MA O 1730

High Efficiency Solar CeJJ Modules

954461

The objective of this work is the fabrication of solar modules having a target conversion efficiency of 13 % (AM 1.5, NOCT). This efficiency goal is based on the use of a large area high efficiency silicon solar cell. The cell design essentiaJJy comprises the Spire Block V cell design, with several efficiency-enhancing features: an improved metalJiza tion pattern, reduced reflectivity and surface recombination, and a back surface reflector intended to reduce NOCT and thereby improve module lifetime.

Measurements on an encapsulated BSR cell shows that 75 % of the sub-bandgap radiation is reflected. Efficiency of the best encapsulated cell measured at the JPL is 17 .1 %. Typical average efficiency of the BSR ceJls being fabricated is 15.5 %.

The module design is characterized by high cell packing factor (90 %). Eighty-four solar cells with an area of 53 cm2 each are used in each module. Overall module dimensions are 91.2 cm x 54.2 cm. The first module has been delivered to the JPL and has been tested. Efficiency is 13.7 % at 25°C (100 mW/ cm2). NOCT measurement is in progress.

Work in progress includes fabrication of mini-modules compnsmg BSR ce11s of various types, including high efficiency texture-etched cells. Efficiency and NOCT wilJ be tested on the mini-moudJes to determine the optimum ceH design from the point of view of both conversion efficiency and module lifetime. Group II modules w i11 then be fabricated.

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Contract Title:

Contract No.:

PROCESS RESEARCH TASK Spire Corporation

Bedford, MA O 1730

Adapt Pulse Excimer Laser Processing Technology to Fabricate Cost Effective Solar Cells 956797

The objective of this contract is to determine whether the ion-implantation and pulsed excimer laser anneal processes, applied to front and back junction formation in silicon solar cells, are cost-effective replacements for phosphorus diffusion and aluminum alloying processes. Research has involved an investigation of laser anneal process parameters, con tact formation to laser annealed wafers (including both evaporated and screen printed contracts), and an economic analysis based on a demonstration run of 300 large-area cells.

This con tract is near completion. The principal findings of this work are the following:

( l)

(2)

(3)

(4)

(5)

(6)

The implantation/ anneal process may be easily applied to non-textured wafers. Cell efficiency of up to 15.6 % has been obtained.

The anneal process is more difficult to apply to textured wafers and requires further development.

The 50 watt laser is capable of processing at speeds of up to 600 wafers/hr.

Laser anneal uniformity is sufficient for fabrication of large-area (53 cm2) cells. Average efficiency of cells, implanted with the Spire non-mass-analyzed SPI-ION 1000, is 9.5 % without AR coating.

Screen printed contacts can be applied to the laser annealed junctions without shunting; adhesion is satisfactory. Efficiency of up to 8.8 % without AR coating has been obtained.

Economic analysis indicates that the efficiency of the laser annealed cells must be higher than furnace annealed cells to be economically competitive.

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Contract Title:

RELIABILITY PHYSICS

SPRINGBORN LABORATORIES, INC. Enfield, Connecticut 06082

INVESTIGATION OF TEST METHODS, MATERIAL PROPERTIES AND PROCESSES FOR SOLAR CELL ENCAPSULANTS

Contract No.: 954527

The goal of this program is to identify, develop and evaluate materials and processes for the low cost encapsulation of silicon photovoltaic cells. Material selections are based on performance criteria and the FSA objec~ tive of achieving a solar flat-plate or concentrator array at a manufactured cost of $0.70 per peak watt ($70/m2) (1980 dollars). Pottant compounds are under continuing development with evaluations of internal primers, UV screen­ers, and HALS stabilizers to optimize performance. Candidate formulations are assessed for relative life performance using accelerated stress environ­ments.

A new accelerated aging method has been developed that combines natural sun­light and elevated temperatures. This technique is termed Outdoor Photo­Thermal Aging Reaction (OPTAR) and is used for aging individual materials as well as whole modules. At the highest temperature (1050C) test bars of industrial pottant formulations degrade within 2,000 hours. Test modules have much higher stability than single materials and have accumulated 12,000 hours of exposure to date. The modules at 1os0c all show conspicuous signs of de­gradation, but still produce power. Modules aged at 700C are virtually un­affected. The OPTAR method has been found to give linear plots of induction period versus temperature (Arrhenius) and may result in a viable method for the prediction of long term aging and lifetime.

Adhesive bonding is essential to module integrity. Springborn Laboratories is continuing to identify primers and adhesives for all the possible inter­faces. Additionally, experimental support is being provided to two Univer­sities for fundamental studies in adhesion science. A hydrothermal aging method appears encouraging for the diagnosis of durability and life assessment of adhesive bonds.

Adequate dielectric strength is an essential polymer property. A new test method has been developed to determine the intrinsic dielectric strength (DC) of polymer materials and this property will be measured during long term aging.

Anti-soiling treatments for the surface of PV modules is still under evalu­ation with the use of outdoor exposures. The fluorosilane treatments still appear to be effective after 3 years of exposure and enhance ~verall module output by about 1%.

Experiments are underway to lower the overall flammability of modules through the use of (a) fire-retardant compounds, (b) reduction of combustible mater­ials, (c) high containment back covers, or (d) a combination of these tech­niques. Special test apparatus is being designed for these evaluations.

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Contract Title:

Contract No.:

STATE UNIVERSITY OF NEW YORK AT ALBANY Albany, New York

Studies of Oxygen- and Carbon-Related Defects in High­Efficiency Silicon Solar Cells

956989

Ve are studying oxygen- and carbon-related defects in silicon, par­ticularly as related to high-efficiency silicon solar cells. Ve are carrying out a survey of these process-induced defects, of life-time measurement techniques, and of defect aggregates in general. Ve are carrying out coordinated experimental and theoretical studies of process­induced defects, which have results listed below., and have initiated a new series of annealing experiments, including flash-lamp heating of "as-received," pre-heat-treated and homogenized samples, using DLTS, IR, TEM, positron annihilation, and, as needed, EPR and x-ray scattering studies. Our studies indicate that the vacancy is the likely source of the anomalous oxygen diffusion observed by Stavola et al., confirmed the identification of the (V + 2 O) center, and indicat~tliat defect-enhanced diffusion (such as in ion-implantation or neutron-transmutation-doping) can lead to thermal donors, and presumably orther impurity complexes. Ve have developed a theory that describes the electrical behavior of the hierarchy of thermally-induced double donors, including a core and an electronically repulsive oxygen-rich region. Ve have identified the most likely core for the homogeneously-nucleated oxygen precipitate as the "ylid," the saddle-point for oxygen diffusion stablized by the presence of two or more additional oxygens. Ve conclude as well that the precipi­tation strain-energy can also cause the emission of an interstitial leaving the core as the (V + 2 O) center; we conclude also that the like­liest interstitial is an unbonded Sil() molecule, which is also the likely interstitial involved in high-temperature and oxidation processes. These processes are consistent with precipitation processes observed in TEM studies by Bourret and others, and with the recombinations centers observed.

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Contract Title:

Contract No.:

ADVANCED MATERIALS RESEARCH TASK UNION CARBIDE CORPORATION

WASHOUGAL, WASHINGTON

Fluid Bed Silane Decomposition R&D

954334

The objective of the current R&D program is to develop fluid bed silane decomposition technology for producing semiconductor grade silicon for photovoltaic application. The principal activities during the current re­porting period were in the following areas:

• design and implementation of a new PDU liner support system, • several long-duration silane decomposition test runs, • design and testing of a new plate-type gas distributor, and • purity evaluation and characterization of product samples.

A new design for supporting and sealing a high-purity quartz or polysilicon liner in the six inch diameter stainless steel reactor was implemented during the early part of this year. Subsequently, the PDU was operated with a quartz liner, and three long-duration test runs were conducted tot­alling over 110 hours of run time. In these runs, the feed silane concentration was nominally in the 20 to 30 percent range, and the operat­ing conditions were smooth and steady. Several kilograms of product samples were generated from these tests. The samples were analyzed by SEM and optical micrographs to study the growth layer thickness and morphology. Purity analysis of the fluid bed product was done by spark source mass spectrometry. Also, a 3 inch diameter single crystal was grown from the sample produced from one of the test runs. Wafers sliced from the single crystal ingot will be analyzed for donor/acceptor concentration levels by photoluminescence spectroscopy.

In all of the above experimental runs, accumulation of fine powder in the fluid bed was found to occur. In an attempt to minimize the generation of these fine particles, the dynapore conical gas distributor was replaced by a perforated plate-type distributor and a silane decomposition test run was conducted. Examination of the product samples from this run indicated a significant reduction in the fines content. Additional tests are planned to confirm the performance of this new distributor.

Future plans include continuation of PDU tests with quartz and/or polysili­con liners to establish product purity. Also, techniques for producing high-purity seed particles for starting the growth cycle in the fluid bed reactor will be evaluated.

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May 20, 1985 Date

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High Efficiency Solar Cell Research F. A. Lindholm and A. Neugroschel, Electrical Engineering Dept.

Contract Title:

Contract No.:

Gainesville, Florida, 32611

Physics of Heavily Doped Silicon and Solar-Cell Parameter Measurement

956525

We report the first use of a (silicon)/(heavily doped polysilicon)/(metal) structure to replace the conventional high-low junction (or BSF) structure of silicon solar cells. Compared with BSF and back-ohmic-contact control samples the polysilicon-back solar cells show strong improvements in red spectral response and modest improvements in open-circuit voltage. The decisive point is that measurement reveals that a decrease in effective surface recombination velocity Sis responsible for these improvements. Decreased S results for n-type (Si:As) polysilicon, consistent with past findings for bipolar transistors, and for p-type ( Si :B) polysilicon, are reported here for the first time (Table 1).

Runs in progress, one of which is completed, will provide details about the use of polysilicon on the front as well as the back surface of solar cells as a potential barrier that provides a partially blocking contact. On special test structures we have demonstrated surface recombination velocities of about 15 cm/s for doping concentrations of the order of 10 16/cc and below 103 cm/s for heaviliy doped silicon when metal was present over the entire area. These results, and a brief indication of the mechanisms yielding them, are obtained on small-area devices. On solar cells having an area of 4 cm2, the results of our first run are as shown in Table l; the lowest value of surface recombination velocity is 100 cm/s. Measurements were made by the transient electrical short-circuit decay technique and corroborated by use of small-signal admittance methods.

A design theory utilizing polysilicon contacts is presented, as well as an indication, following Sah, of a practical limit efficiency of 23%.

In addition to the polysilicon related work, we provide new information about the measurement of Auger lifetime, about minority-carrier diffusivity in heavily doped silicon, and about improved measurements of recombination parameters from observing voltage transients.

May 17 2 1985 Approve I Signature Date

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Contract No.:

ADVANCED MATERIALS RESEARCH TASK University of Illinois at Chicago

Chicago, Illinois 60680

Surface Property Modification of Semiconductors by Fluid Adsorption 95653

The objectives of this study are: (a) develop an understanding of the basic mechanisms of abrasion and wear of silicon and {b) to continue studies of the nondestructive measurement of residual stresses in sheet silicon.

The results of our work to date may be summarized as follows:

1. We have been developing a technological base for improving the cutting efficiency of silicon by abrasive wear. Abrasive wear refers to the relative motion usually in the presence of a fluid of a hard particle with a substrate. This sliding results in microcracks and a plastic zone in the vicinity of the contact area. The extent of this damage depends on the contact force, sliding speed and fluid in contact with both surfaces. We have constructed two apparatuses for single point, slow speed scratching and multi-point, high speed scratching of silicon. The temperature of the silicon and fluid may be varied.

We have shown that

(a) The sliding damage depends on the load and fluid environment. TEM analysis has shown that dislocations, microtwins and cracks are generated beneath the contact surface.

(b) Indentation at room t.emperature of silicon is being used to study sub­surface damage. Dislocation rosettes are generated when indentations are annealed. The rosette sizes are related to annealing conditions and environmental parameters. EBIC experiments have revealed sub­surface damage due to indentations.

(c) Dynamic friction experiments have been carried out and the friction coefficient has been measured in various fluids. These experiments show that dynamic friction is indicative of the deformation mode of silicon.

(d) A surface state model has been developed that accounts for 'the in­fluence of dopant, temperature and fluid properties on abrasive wear of silicon.

2. Residual stresses of Mobil EFG ribbon have been measured utilizing a shadow Moire interferometry technique. The code used for determining residual stresses from strain measurements has been improved and automated.

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Contract Title:

Contract No.:

Stress-Strain-Buckling University of Kentucky

Lexington, KY

Stress-Strain Analysis of Silicon Ribbon

956571

We have obtained two really major improvements in understanding the growth process of silicon ribbon. We have made numerous good numerical solutions for the stresses, strain rates and dislocation density at each point in the ribbon. More importantly, we have ascertained that many cases of the com­puter solutions failing to converge are analytical manifestations of shear bands (Luder's) observed in experiments. Observations of EFG ribbon show 11 jumps 11 in the displacements which violates compatability. The numerical values in the computer solution are roughly those observed by Mobil Solar. The most basic scientific contributions here are the use of the Sumino model for having a changing dis.location density. This is essential for the case of a material where one wants to insure that the dislocations stay low in value.

The second major improvement is in the buckling area and in particular in buckling in the plastic domain. We have shown that plasticity controls whether buckles increase in time or decrease in value. This is the first time that we are aware of that such results have been found.

Furthermore each mode that grows does so at different rates. Thus the mode most likely to be observed is the one that grows fastest. Which mode grows fastest depends on the geometry and the thermal profile.

The reason that some modes damp out rather than grow is that we have no loads on the ribbon whereas previous investigators of creep buckling normally have prescribed loads on the ends.

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Contract Title:

Contra ct No.:

HIGH EFFICIENCY SOLAR CELL RESEARCH University of Pennsylvania

Philadelphia, PA

Development and Analysis of Silicon Solar Cells of Near 20% Efficiency 956290

The objective of this contract is to identify, assess, and demonstrate use­ful techniques for measuring bulk recombination rates and surface recombin­ation velocities in all regions of high efficiency Si solar cells. For this purpose, our program has been based on identifying and extending those re­combination measurement methods, which were formerly designed to determine a single recombination parameter, which can be used for extracting multiple recombination parameters. The first step of classifying and categorizing recombination parameter measurement methods has been completed. The methods were classified by basic physical process, number of external variable para­meters, depth resolution, and physical assumptions made or required for in­terpretation of the measured data. During the last 6 months, the work has also been concentrated on the development of the "Spectral Modulated Light Method" (SMLM).

In the preceding work, we have demonstrated the usefulness of ASLBIC for measuring the recombination parameters throughout a solar cell. The major disadvantage of the method is the need for absolute intensity calibration. We expected the SMLM method to replace this calibration requirement by eas­ier measurements at multiple modulation frequencies. Thus, we are develop­ing (as a first) a method using monochromatic intensity modulated light at various wavelengths to generate an ac short circuit current. The short cir­cuit current is measured by the voltage developed across a small load resis­tance at the input of a high frequency lock-in amplifier. Changing the mod­ulation frequency, the device's frequency response is measured in amplitude and phase. These data can be reduced to yield the surface recombination velocity and the diffusion lengths in different parts of the device. In the present approach, LED's of different colors are used as the modulatable light source. One or more modulated, tunable laser(s), being capable of providing higher light intensity, are foreseen for future expansion of this method. In recent measurements on whole 2 cm x 2 cm solar cells, the junc­tion capacitance has dominated the response at frequencies below those in­fluenced by the recombination mechanisms. Its influence can be shifted to orders of magnitude higher frequencies by reducing~ a)the load resistance; b)the junction area. These changes do not influence the frequency response due to recombination. Also, the recombination-caused amplitude change and phase-shift could be extracted from a frequency response influenced by the junction capacitance. These approaches are currently being explored. Their application seems, so far, to be somewhat limited by the moderate light in­tensity available from the LED's but should be greatly eased by use of the laser source(s).

May 14, 1985 Date

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Contract Title:

Contract No.:

DEVICE AND MEASUREMENTS RESEARCH TASK JOINT CENTER FOR GRADUATE STUDY

RICHLAND, WA 99352

Investigation of High Efficiency Silicon Solar Cells

956614

The primary objectives of this program are to investigate hi~h efficiency silicon solar cells, and to develop experimental techniques for passivating surfaces of silicon cells. The approach consists of: (1) design and fabrication of high efficiency cells based on an MINP structure; (2) detailed analyses of photocurrent and current-voltage characteristics of high efficiency cells; (3) and investigation of approaches to passivate silicon surfaces, with particular emphasis on PECVD deposited SiNx.

High efficiency silicon cell work has concentrated on photocurrent improvement, emitter optimization studies, and analysis of current-voltage characteristics. To improve photocurrent, collector grid shadowing has been reduced from 6% to 3.5% and a double AR structure based on Ti02 and MgF2 has been developed. These features are currently being incorporated into the MINP cell structure. Another area of investigation concerns the development of an optimum emitter dopant concentration. The possibility of using ion implantation to achieve a shallow junction with sufficiently low sheet resistance, and a minimum concentration of unactivated phosphorus at the surface is being pursued. The process simulation computer code SUPREM is used to calculate the effects of ion dose, ion energy and annealing. Several promising implant/anneal schedules have been identified. Current-voltage analyses have been conducted on numerous efficient cells in an effort to understand limiting current mechanisms. MINP cells based on 0.2 n-cm material with 0.2 µm deep junctions typically exhibit dark I-V characteristics which are understood in terms of emitter recombination (including band gap narrowing effects). We observe, however, that under illumination, 1-V characteristics typically change.

Surface passivation studies have concentrated on development of measurement techniques. In particular, a slow ramp capacitance measurement waJ0deve~oped1which allows one to measure interface densities less than 10 cm- ev-. Efforts were also devoted to development of a gated diode measurement. In principle, one can measure the interface density on the N+ surface of an N+/P solar cell. Several cells have been examined by first depositing SiNx on a cell surface, and then defin1ng a contact pattern to allow deposited Mg to contact the N+ surface layer. Aluminum dots are then deposited onto SiNx. High frequency yjV measurements are then cy5rie2 out. Prelimin9ry results indicate D

55 = 10 • If one assumes a= 10- cm,

Vth = 10 cw/sec. The surface recombination velocity (S) is estimated to be= 3 x 10 cm/sec. This value agrees well with results obtained from photoresponse measurement and analysis.

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Contract Title:

Contract No.:

ADVANCED SILICON SHEET TASK WESTINGHOUSE ADVANCED ENERGY SYSTEMS DIVISION

Pittsburgh, PA 15236

Advanced Web Growth Development

955843

The overall objective of this program is to develop silicon web growth tech­nology consistent with the area rate and efficiency requirements necessary to meet the JPL/DOE goals for terrestrial photovoltaic applications. Among the contract milestones are the demonstration of area growth rates of 13 cm2/min and 16 cm2/min with a constant melt level and the demonstration of web growth under closed loop control.

Computer analysis of the thermal environment surrounding the web crystals in­dicated that significant stress reduction could be achieved by the placement of a vertical thermal element (VTE) at the position where the web exits the heat shield stack and enters the cooler furnace ambient. This analysis has been verified experimentally by growth of a 6.7 cm wide web only 160 µm thick. This web is nearly a centimeter wider than the widest previous crystal and is indicative of significant stress reduction. A steady state area rate of 8 cm2/min was also achieved. Optimization of the VTE tem~erature and dimen­sions is underway.

Characterization of silicon webs grown from the new configuration indicate that the material exhibits relatively low residual stress and etch pit densi­ty (EPD). Residual stress values measured by the split width technique range from 1 to 9 Mdyn/2m2, and EPD values are typically to 5,000 cm-2. EDP values as low as 100 cm- have been measured.

We have identified and successfully tested a vidicon-based system for sensing changes in the web dendrite thickness, a oarameter which relates directly to changes in melt thermal environment. By measuring dendrite thickness changes we obtain an error signal which can be used for feedback to adjust melt tem­perature and coil position thus providing the basis for a closed loop system operation.

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Contract Title:

Contract No.:

Advanced Module Development WESTINGHOUSE ELECTRIC CORPORATION Advanced Energy Systems Division Pittsburgh, PA 15236

DENDRITIC HEB-TYPE SOL'\R CELL MrnI-MODULES

957193

The pur~ose of this program is to fabricate twenty-five mini-modules using dendritic web silicon solar cells. These mini-modules are to be used for environmental testing.

The mini-modules, with a nominal size of 12 cm x 40 cm, will be identical with respect to materials, manufacturing, and assembly processes to a full scale module. The electrical circuit is a 15 cell series string, each cell being 2.5 cm x 9.8 cm. Cell-to-cell spacing, as used in a full size module, will be maintained. The power output will be proportional to a full scale module.

The modules will be delivered to J~L in July for a series of environmental tests.

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Contract Title:

Contract No.:

Process Development/Advanced Processes Westinghouse R&D Center Pittsburgh, PA 15235

Laser-Assisted Solar Cell Metallization Processing

956615

The objective of this program is to develop and characterize laser-assisted techniques to produce fine metal grid lines for efficient solar cells and demonstrate the successful fabrication of high-efficiency solar cells.

Argon-ion laser-assisted thermal decomposition of silver neodecanoate metallo-organic ink has so far been found as the most promising laser­assisted metallizatign scheme.

0The complete metallization process consists

of evaporating 1500 A Ti+ 500 A Pd followed by spinning a thin layer of silver neodecanoate film. A grid pattern is then written by laser decomposition of this film, which leaves a few hundred angstroms of silver only in the grid region. The remainder of the film Ti and Pd is removed from the rest of the wafer and grid lines are subsequently silver plated.

An evaporated double-layer antireflective coating is applied, which is compatible with the laser-assisted metallization process. Without any oxide passivation, greater than 16% efficient solar cells were fabricated on 4 ohm-cm float-zone silicon wafers. The grid linewidth was~ 70 microns, which is appreciably wider than the optimum design of 25 microns. Attempts are being made to reduce the linewidth by reducing the laser power and changing the lens.

In an attempt to demonstrate greater than 17% efficient cells by the laser-assisted metallization process, cells are now being fabricated on high-quality 0.25 ohm-cm float-zone silicon. Attempts are also being made to incorporate oxide passivation by either growing a thin tunnel oxide all over or by laser zapping the passivating oxide underneath the grid lines.

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HIGH-EFFICIENCY SILICON SOLAR CELL RESEARCH Westinghouse R&D Center Pittsburgh, PA 15235

Contract Title: Development of High-Efficiency Solar Cells on Silicon Web

Contract No.: 956786

The objective of this program is to improve web base material with a goal toward obtaining solar cell efficiencies in excess of 18%. The program con­sists of the investigation of carrier loss mechanisms in web silicon, development of techniques to reduce carrier recombination in web, and web cell fabrication using effective surface passivation and double-layer anti­reflective coating.

Recent model calculations show that 150 micron thick 4 ohm-cm web solar cells need a minority carrier diffusion length greater than 400 microns in order to achieve 17.5% efficiency. However, 0.2 ohm-cm web cells require a diffusion length of only 125 microns to produce the same efficiency. These calculations assume oxide passivation and double-layer AR coating.

A combination of oxide passivation, back-surface reflector, and double-layer antireflective coating gave 16.2% efficient solar cells on 4 ohm-cm web crytals. The measured diffusion lengths were in the range of 250-300 microns. Several low-resistivity web crystals were also grown and advanced cell processing on these crystals resulted in cell efficiencies in excess of 16.5%. The diffusion length in these crystals was in the range of 100-150 microns.

Electron Beam-Induced Current (EBIC) or LBIC measurements on beveled web surfaces revealed some electrical activity or enhanced recombination at the twin planes in web crystals. The impact of this activity on web cell performance is being investigated. Preliminary DLTS measurements as a function of depth suggest weak impurity/twin-plane interaction. Investiga­tion of microstructural defects has shown the presence of saucer defect in addition to the dislocations, which may account for the small diffusion length in as-grown web crystals.

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CONTRACTOR

APPLIED SOLAR ENERGY CORP.

APPLIED SOLAR ENERGY CORP.

APPLIED SOLAR ENERGY CORP.

ARCO SOLAR, INC.

ARCO SOLAR, INC.

ARIZONA STATE UNIVERSITY

ASTROSYSTEKS, INC.

C.T. SAH ASSOCIATES

CALIFORNIA INST. OF TECH.

CALIFORNIA INST. OF TECH.

CLEMSON UNIVERSITY

CORNELL UNIVERSITY

ELECTRlNK, INC.

FSA PROJECT ACIVE CONTRACT STATUS LIST

TITLE

SOLAR-CELL PROCESS DEVELOPMENT

LABORATORY SERVICES

DEVELOPMENT OF HIGH-EFFICIENCY SOLAR CELLS

ADAPT PULSED EXCIKER LASER PROCESSING TECHNOLOGY TO FABRICATE SOLAR CELLS

BLOCK V DOCUMENTATION AND SOLAR CELL MODULES

CONDUCT AN EVALUATION AND CALIBRATION OF A CZOCH_RALSKI CRYSTAL-GROWTH SYSTEM

SILICON-FILM SOLAR-CELL PROC~SS

RELATIONSHIPS OF MATERIAL PROPERTIES AND HIGH-EFFICIENCY SOLAR CELL PERFORMANCE ON MATERIAL COMPOSITION

DIFFUSION BARRIER STUDIES

INVESTIGATION OF FREE-SPACE REACTOR SILICON PRODUCTION

INVESTIGATION OF RELIABILITY ATTRIBUTES AND ACCELERATED STRESS FACTORS ON TERRESTRIAL SOLAR CELLS

INVESTIGATION OF PHYSICAL STRUCTURE AND THE CHEMICAL NATURE OF DEFECTS IN SILICON SHEET MATERIAL

DEVELOPMENT AND CHARACTERIZATION OF SCREENABLE MATERIALS UTILIZED IN THE FABRICATION OF SOLAR CELLS

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EXPECTED CONTRACT START CLOSURE

NUMBER DATE DATE

955089 05/31/78 12/84

955423 03/03/79 10/85

956098 12/13/84 01/86

956831 05/04/84 06/85

956336 11/04/82 02/85

956876 06/01/84 07 /85

956769 02/06/84 10/84

956289 07/01/82 10/86

W061517 07/00/82 07/84

W061515 08/00/80 09/84

954929 12/09/77 10/85

956046 06/22/81 08/85

956985 07/24/84 08/85

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D D

ENEHGY KATEI.UALS CORP. TECHNOLOGY DEVELOPMENT F'OR LOW-ANGLE SILICON SHEET (LASS) GROWTH TECHNIQUE 1''0R PHOTO-­VOLTAIC APPLICATIONS

MASSACHUSETTS INST. OF TECH. STUDY AND ANALYSIS OF HIGH-SPEED GROWTH OF SILICON SHEETS IN INCLINED MENISCUS CONJHGURATIONS

MOBIL SOLAR ENERGY CORP. EDGE-DEFINED FILM-FED GROWTH TECHNIQUE

NORTH CAROLINA AT&T EFFECTS OF ROW-TO-ROW SHADING ON PHOTOVOLTAIC ARRAYS

PENNSYLVANIA STATE UNIV. USE OF LOW-ENERGY HYDROGEN ION IMPLANTS IN HIGH-EFFICIENCY CRYSTALLINE-SILICON SOLAR CELLS

956822

956919

956312

957021

956126

POLYTECHNIC INST. OF NEW YORK DEVELOPMENT AND DEMONSTRATION OF 956413 SYNTHETIC PROCEDURES FOR POLYMERIC ULTRAVIOLET STABILIZERS AND ABSORBERS

PURDUE RESEARCH FOUNDATION MOD SILVER METALLIZATION FOR 956679 PHOTOVOT.TAICS

PURDUE RESEARCH FOUNDATION lNK-JET PRINTING OF SILVER 957031 METALLIZATION FOR PHOTOVOLTAICS

RESEARCH TRIANGLE INST. COMPREHENSIVE SILICON SOLAR CELL 956741 COMPUTER MODELING

SCANNING ELECTRON ANALYSIS MATERIAL ANALYSIS OF PHOTOVOLTAIC 956752 LABORATORY (SEAL)

SOLAR ENERGY RESEARCH INST. PURIFICATION OF METALLURGICAL- W08747 GRADE SILICON BY CHEMICAL VAPOR TRANSPORT

SOLAR ENERGY RESEARCH INST. OPTIMIZATION OF SILICON W08762 CRYSTALS FOR HIGH-EFFICIENCY SILICON SOLAR CELLS

SOLAREX CORP. BLOCK V DOCUMENTATION AND SOLAR 956333 CELL MODULES

SOLENERGY CORP. INTERMEDIATE-LOAD MODULES FOR 046347 TEST AND EVALUATION

SPECTROLAB, INC. DESIGN, ANALYSIS AND TEST 955567 VERIFICATION OF ADVANCED ENCAPSULATION SYSTEMS

54

02/12/84 06/85

06/20/84 06/86

17/09/82 12/85

09/28/84 10/85

03/07/85 01/86

01/03/83 12/85

11/17/83 05/85

09/27/84 03/85

01/05/84 03/85

01/06/84 01/85

08/00/83 07/85

09/00/84 09/85

09/20/82 03/85

09/22/82 11/84

11/08/79 12/85

D D

SPh:CTROLAB, INC.

SPIRE CORP.

SPIRE CORP.

SPIRE CORP.

SPRINGBORN LABORATORIES, INC.

STANFORD UNIVERSITY

STATE UNIV. OF NEW YORK­ALBANY

SUPERWAVE TECHNOLOGY, INC.

UNDERWRITERS LABORATORIES, INC.

UNION CARBIDE CORP.

UNIVERSITY OF CALIFORNlA­SANTA CRUZ

UNIVERSITY OF FLORIDA

UNIVERSITY OF ILLINOIS

UNIVERSITY OF KENTUCKY

UNIVERSITY OF PENNSYLVANIA

UNIVERSITY OF PENNSYLVANIA

DEVELOPMENT OF METALLIZATION PROCESS

HIGH-EFFICIENCY SOLAR CELL MODULES

ADAPT PULSED EXCIMER LASER PROCESSING TECHNOLOGY TO FABRICATE COST-·EFFECTIVE TECHNOLOGY

BLOCK V DOCUMENTATION AND SOLAR CELL MODULES

MODULE ENCAPSULATION TASK

lNTERFACIAL BARRIERS IN HIGH­EFFICIENCY CRYSTALLINE SILICON SOLAR CELLS

STUDIES OF OXYGEN AND CARBON­RELATED DEFECTS ON SILICON SOLAR CELLS

DEMONSTRATION OF FEASIBILITY OF DEPOSITING SEMICONDUCTOR LAYERS USING MICROWAVE TECHNOLOGY

INVESTIGATION OF PHOTOVOLTAIC MODULES AND ARRAY MATERIALS

SILANE-TO-SILICON PROCESS

TIME-RESOLVED SPECTROSCOPIC MEASUREMENTS

SURFACE AND ALLIED STUDIES IN SILICON SOLAR CELLS

STUDY OF THE ABRASIVE WEAR RATE OF SILICON

STRESS-STRAIN ANALYSIS OF SIL1CI0N RIBBON

DEVELOPMENT AND ANALYSIS OF SILICON SOLAR CELLS OF NEAR 201» EFFICIENCY

CHAIRMAN OF ADVISORY COMMITTEE ON LOW-·COST SOLAR CELLS

55

956205

956641

956797

956334

954527

956960

956989

956828

956368

954334

956467

956525

953053

9565 71

956290

956166

04/05/82 09/84

10/06/83 06/85

03/22/84 03/85

12/09/82 02/84

05/12/76 08/86

10/05/84 11/85

09/19/84 08/86

03/01/84 12/84

11/16/82 10/85

10/06/15 06/85

03/07/83 PENDING

06/24/83 07/86

06/18/81 08/85

06/23/83 08/85

08/31/82 01/86

01/05/8:? 12/85

~ u

~

UNlVERSITY OF TORONTO

~ UNIVERSITY OF WASHINGTON

D WASHINGTON UNVERSlTY AT

r1 u

ST. LOUIS

WESTINGHOUSE ELECTRIC CORP.

WESTINGHOUSE ELECTRIC CORP.

MODELING OF PHOTOOEGRADATION IN SOLAR-·CELL MODULES OF SUBSTRATE AND SUPERSTRATE DESIGN MADE WITH ETHYLENE-VINYL-ACETATE POTTANT MATERIAL

lNVESTIGATION OF SILICON INVERSION-LAYER SOLAR CELLS AND CARRIER LIFETIME MEASUREMBNTS

955591

955614

MODELING OF FLUlDIZED--BEO REACTORS 956 73 7 FOR PRODUCTION OF SILICON FROM S!LANE

PROCESSING OF NON-CZOCHRALSKl SILICON KAT£e~RIAL

DEVELOPMENT OF HIGH-EFFICIENCY SOLAR CELLS ON SILICON WEB

956616

956786

WESTINGHOUSE ELECTRIC CORP. LASER--SSISTED SOLAR CELL 956615

D D

D .

n tJ

METALLIZATION PROCESSING

WESTINGHOUSE ELECTRIC CORP. DENDRITIC--WEB PROCESS DEVELOPMENT 955843

WILKES COLLEGE

WYLE LABORATORIES

ELECTROCHEMICAL RESEARCH ON SOLAR CELLS AND PHOTOVOLTAIC MATERJAJ. .. S

TECHNICAL SUPPORT IN THE DEVELOPMENT OF DURABILITY/ RELIABILITY PERFORMANCE CRITERIA ANO TEST METHODS FOR ARRAY SUBSYSTEM ELEMENTS

56

956766

955853

01/02/80 05/86

08/22/83 09/85

12/05/83 06/85

11/04/83 07/85

03/20/84 03/86

08/13/83 11/85

10/22/80 03/85

02/09/84 02/86

08/18/80 09/84

[] I .

1 Kay 1985

Document Number

5040-29 ERDA/JPL-1012-76/3

5101-2 ERDA/JPL-1012-76/1

5101-5 ERDA/JPL-1012-76/4

5101-7 ERDA/JPL-1012-76/6

5101-8 ERDA/JPL-1012-76/7

5101-10 ERDA/JPL-1012-77/1

5101-12

5101-13

5101-14

5101-15'

FSA PUBLIC DOCUMENTS

Author/Date

Doane, J. W. June, 1976

PROJEC'I OFFICE January, 1976

PROJECT OFFICE April, 1976

PROJECT OFFICE October 8, 1976

PROJECT OFFICE July 30, 1976

PROJECT OFFICE

Zoutendyk, J. October 28, 1976

Gonzalez, c. c. February 14, 1977

Edelson, E. January 26, 1977

Chamberlain, R. G. September 1977

57

Prepared by: FSA Data center ext. 9519

Document Title

The Cost of Energy From Utility-owned Solar Electric Systems

Proceedings of the First Task Integration Meeting

Proceedings of the Second Project Integration Meeting

LSA First Quarterly Report - April 1976 to June 1976

Proceedings of the Third Project Integration Meeting

LSA Second Quarterly Report - July 1976 to September 1976

Progress in Silicon Crystal Technology for Terrestrial Photovoltaic Solar Energy Conversion

Availability of Ultraviolet Radiation Data (for Encapsulation System Design)

Preliminary Analysi's of Industrial Growth and the Factors That Affect Growth Rate

Samics (Solar Array Manufacturing Costing Standards) Workbook

D

0

5101-16 Rev. A DOE/JPL-1012-78/10

5101-19

5101-20

5101-21 Rev. B

5101-24 ERDA/JPL-1012-77/2

5101-31

5101-32 DOE/JPL-1012-77/3

5101-33

5101-36

5101-39

5101-40

5101-43

FSA PUBLIC DOCUMENTS

LSA. ENGR. AREA November 1, 1978

Moore, D. February 28, 1977

Cantu, A. H. February 28, 1977

Bishop/Anhalt November 3, 1978

PROJECT OFFICE

Stultz/Wen July 29, 1977

PROJECT OFFICE

Aster/Chamberlain September 10, 1977

Smokler, N. October 15, 1977

Jaffe, P. August 3, 1978

Coulbert, C. D. June 8, 1977

Grippi, R. A. October 7, 1977

58

Block IV Solar Cell Nodule Design and Test Specification for Intermediate Load Center Applications

Cyclic Pressure - Load Developmental Testing of Solar Panels

Test Program on Low-Cost Connector for Solar-Array Nodules

Acceptance/Rejection Criteria for JPL/LSA Modules

Project Quarterly Report - 3 for the Period October 1976 to December 1976

Thermal Performance Testing and Analysis of Photovoltaic Modules in Natural Sunlight

Quarterly Report - 4 for the Period January 1977 to March 1977

Interim Price Estimation Guidelines: A Precursor and an Adjunct to SAMIS III, Version One

User Handbook for Block II Silicon Solar Cell Modules

LSA Field Test Activity System Description

Development & Validation of A

Life-Prediction Methodology for LSA Encapsulated Modules

Module Efficiency Definitions, Characteristics and Examples

fl IJ

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5101-45

5101-46 DOE/JPL-1012-77/4 JPL Publ. #78-9

5101-51

5101-53 DOE/JPL-1012-77/6

5101-54 Vol. I DOE/JPL-1012-78/1

5101-54 Vol. II DOE/JPL-1012-78/1

5101-55 DOE/JPL-1012-78/2

5101-56 DOE/JPL-1012-78/3

5101-57 DOE/JPL-1012-78/7

5101-58

5101-59

FSA PUBLIC DOCUMENTS

Gonzalez, c. C. December 6, 1977

PROJECT OFFICE June, 1977

Praturi/Lutwack/ Hsu July 17, 1977

O'Donnell/Leipold/ Hagan March 1, 1978

Smith, J. L. April 1978

Smith, J. L. March 1, 1978

PROJECT OFFICE

Turner, G. B. March 1, 1978

Chen, c. P. February 22, 1978

Estey, R. s. March 15, 1978

Chamberlain/Aster February 1, 1978

59

Environmental Hail Model for Assessing Risk to Solar Collectors

Project Quarterly Report-5 for the Period April - June 1977

Chemical Vapor Deposition of Silicon from Silane Pyrolysis

Compatability studies of Various Refractory Materials in Contact with Molten Silicon

Historical Evidence on Importance to the Industrialization of Flat-Plate Silicon Photovoltaic Systems: Executive Sununary

Historical Evidence of Importance to The Industrialization of Flat-Plate Silicon Photovoltaic Systems

Project Quarterly Report-6 for the period July 1977 - September 1977

Structure of Deformed Silicon and Implications for Low Cost Solar Cells

Multi-Wire Slurry Wafering Demonstrations

Measurement of Solar and Simulator Ultraviolet Spectral Irradiance

SAMICS usage Update No. 1

n

0

D D

Q

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5101-60 Rev. B

5101-61

5101-62 DOE/JPL-1012-78/6

5101-65 D0E/JPL-1012-78/7A

5101-68 Rev. A DOE/JPL-1012-47 JPL Puhl. #80-51

5101-69

5101-70 Rev. B

5101-71 Rev. B

SlOl-72

5101-73 DOE/JPL-1012-78/8

FSA PUBLIC DOCUMENTS

Metcalf, M. s. April 21, 1980

Cuddihy, E. April 13, 1978

Moore/Wilson October 15, 1978

LSA ENGR. AREA Karch 24, 1978

Aster, R. W. January 15, 1980

Daud/Koliwad June 1S, 1978

Standard Assembly-Line Manufacturing· Industry Simulation (SAMIS) Computer Program User's Guide-Release 3 Release 2

Encapsulation Material Trends Reliability 1986 Cost Goals

Photovoltaic Solar Panel Resistance to Simulated Hail

Photovoltaic Module Design, Qualification and Testing Specification

Price Allocation Guidelines January 1980

Effect of Grain Boundary in Silicon Sheet on Minority carrier Diffusion Length and Solar Cell Efficiency

Chamberlain/Firnett Standard Assembly-Line Manufacturing /Horton Industry Simulation SAMIS Design April 21, 1980 Document Release 3

Chamberlain, R. G. April 21, 1980

Maxwell, H. June 15, 1978

Von Roos, O. Kay 31, 1978

60

Standard Assembly-Line manufacturing Industry Simulation (SAMIS) Computer Program Source Code/Release 3

Encapsulant Candidate Materials for 1982 Cost Goals

Determination of Bulk Diffusion Lengths for Angle-Lapped Semiconductor Material via the Scanning Electron Microscope· A Theoretical Analysis

a . '

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5101-75

5101-76 DOE/JPL-1012-78/9

5101-77

5101-79

5101-81 DOE/JPL-1012-78/13

5101-82 DOE/JPL-1012-79/6

5101-83 DOE/JPL-1012-78/14

5101-84 DOE/JPL-1012-78/11

5101-85 DOE/JPL-1012-78/12

5101-88 DOE/JPL-1012-2 JPL Puhl. 1179-14

FSA PUBLIC DOCUMENTS

Smith, J. L. Kay 30, 1978

Stultz, J. W. July 31, 1978

Gupta, A. August 10, 1978

Gupta, A. August 18, 1978

PROJECT OFFICE November 15, 1978

Smokler, M.I. February 1, 1979

LSA ENGR. AREA November 1, 1978

Hoffman/Miller October 15, 1978

Jaffe, Peter September 15, 1978

PROJECT OFFICE

61

The Penetration of the International Market by Domestically Produced Photovoltaic Power Systems: A Survey of Recent Estimates

Thermal and Other Tests of Photovoltaic Modules Performed in Natural Sunlight

Photodegradation of Polymeric Encapsulants of Solar Cell Modules

Effect of Photodegradation on Chemical Structure and Surface Characteristics of Silicon Pottants Used in Solar Cell Modules

Project Quarterly Report-7 for the Period October 1977-December 1977

User Handbook for Block III Silicon Solar Cell Modules

Block IV Solar Cell Module Design and Test Specification for Residential Applications

Bias-Humidity Testing of Solar Cell Modules

LSA Field Test Annual Report August 1977- August 1978

Project Quarterly Report-8 for the Period of January - March 1978

~ .

I

W11 lJ

a

a n 0 D D

0

5101-91, Vol. I DOE/JPL-1012-25,Vol.1 JPL Puhl. #79-103,Vol.1

5101-91, Vol. II DOE/JPL-1012-25,Vol.2 JPL Puhl. #79-103,Vol.2

5101-91, Vol. 111 OOE/JPL-1012-25,Vol.3 JPL Puhl. #79-103,Vol.3

5101-93 DOE/JPL-1012-79/5 JPL Puhl. #78-98

5101-94 OOE/JPL-1012-78/17

5101-96 DOE/JPL-1012-23

5101-98 OOE/JPL-1012-79/1

5101-99 DOE/JPL-1012-3

5101-100 DOE/JPL-1012-4 JPL Puhl. #179-16

5101-102

FSA PUBLIC DOCUMENTS

Smith, J. H. January 15, 1980

Smith, J. H. January 15, 1980

Smith, J. H. January 15, 1980

Chamberlain, R. G. January 15, 1979

Aster, Robert December 1, 1978

Tsou/Schwartz Karch 1, 1979

Griffith, Johns. January 1, 1979

PROJECT OFFICE

PROJECT OFFICE

Slonski, K. L. February 15, 1979

62

Handbook of Solar Energy Data for South-Facing Surfaces in the United states-Volume I: An Insolation, Array Shadowing, and Reflector Augmentation Model

Handbook of Solar Energy Data for South-Facing Surfaces in the United States-Volume II: Average Hourly and Total Daily Insolation Data for 235 Localities (Alaska-Montana)

Handbook of Solar Energy Data for South-Facing Surfaces in the United States-Volume III: Average Hourly and Total Daily Insolation Data for 235 Localities (North Carolina-Wyoming)

A Normative Price for A Manufactured Product: The SAMICS Methodology Volume I: Executive Summary/Volume II: Analysis

Economic Analysis of A candidate 504/WPK Flat~Plate Photovoltaic Manufacturing Technology

Module Performance Assessment: Laboratory and Field Environment

Environmental Testing of Block II Solar Cell Modules.

Project Quarterly Report-9 for the Period April - June 1978

Project Quarterly Report-10 for the Period July - September 1978

Energy Systems Economics Analysis (ESEA) Methodology & User~s Guide

D D 0 D Fl lJ

D D D 0

5101-103 DOE/JPL-1012-79/SA

5101-104 D0E/JPL-l0l2-79/7B

5101-105 DOE/JPL-1012-20

5101-106 DOE/JPL-1012-21

5101-107 DOE/JPL-1012-18

5101-108 DOE/JPL-1012-19

5101-109 DOE/JPL-1012-26

5101-112 DOE/JPL 1012-27

5101-131 DOE/JPL-1012-49 JPL Pub. #80-87

5101-133 DOE/JPL-1012-29 JPL Publ. #79-88

5101-134 DOE/JPL-1012-30 JPL Publ. #79-96

FSA PUBLIC DOCUMENTS

Repar, John February 15, 1979

Goldsmith/Bickler August 30, 1978

Praturi, A. K. April 15, 1979

Praturi, A. K. April 1, 1979

Rhein, Robert A. April 15, 1979

Rhein, Robert A. April 15, 1979

PROJECT OFFICE

PROJECT OFFICE

Hoffman/Maag November 1, 1980

PROJECT OFFICE

Griffith, J. S. September 1, 1979

63

Experience with Silicones in Photovoltaic Modules

LSA Project Technology Development Update

Modeling of Silicon Particle Growth; A Progress Report

On the Modeling of Silane Pyrolysis in A Continuous Flow Reactor

Purification of Silicon by the Silicon Fluoride Transport Process-A Thermo­chemical Study

Silicon Preparation and Purity from the Reaction of Sodium with Silicon Tetrafluoride and Silicon Tetra­chloride-A Thermochemical Study

11th Project Integration Meeting Quarterly Report for 10/12/78

Progress Report 12 for the period January to April 1979 and Proceedings of the 12th Project Integration Meeting

Photovoltaic Module Soiling studies May 1978-0ctober 1980

Progress Report 13 for the period April 1979 to August 1979 and Proceedings of the 13th Project Integration Meeting

Environmental Testing of Block III Solar Cell Modules/Part I: Qualification Testing of Standard Production Modules

0 0 .

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5101-135 DOE/JPL-1012-31 JPL Publ. # 79-92

5101-137 DOE/JPL-1012-32 JPL Publ. #79-102

5101-138 DOE/JPL-1012-36

5101-139 DOE/JPL-1012-34 JPL Publ. #79-116

5101-141 DOE/JPL-1012-38 JPL Publ. #80-5

5101-142 DOE/JPL-1012-42 JPL Publ. #80-21

5101-143

5101-144

5101-146 DOE/JPL-1012-37 JPL Pub. 1180-25

5101-147 DOE/JPL-1012-40 JPL Publ. #80-12

FSA PUBLIC DOCUMENTS

Laue/Gupta Septmber 21, 1979

Chen, C. P. October 15, 1979

LSA ENGINEERING January 15, 1980

Salama, A. M . November 1, 1979

Jaffe, Peter December 15, 1979

PROJECT OFFICE

PROJECT OFFICE January 1980

Cuddihy,E. F. January 15, 1980

Leipold/Radics/ Kachare February 15, 1980

Bouquet, F. L. February 1, 1980

64

Reactor for Simulation and Acceleration of Solar Ultraviolet Damage

Fracture Strength of Silicon Solar Cells

1982 Technical Readiness Module Design and Test Specification-Intermediate Load Applications

Characterization of Deliberately Nickel-Doped Silicon Wafers and Solar Cells

LSA Field Test Annual Report August 1978 - August 1979

Progress Report 14 for the Period August 1979 to December 1979 and Proceedings of the 14th Project Integration Meeting

Electricity From Photovoltaic Solar Cells/Status of Low-Cost Solar Array Project

Encapsulation Materials Status to December 1979

Cost of Czochralski Wafers as A Function of Diameter

Glass for Low-Cost Photovoltaic Solar Arrays

0 0 a Q

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5101-148 DOE/JPL-1012-41 JPL Publ. #80-34

5101-150

5101-151 DOE/JPL-1012-44 JPL Publ. #80-27

5101-154

5101-155

5101-156 Rev. A

5101-158 Rev. A.

5101-159 Rev. A.

5101-160 DOE/JPL-1012-51 JPL Publ. #80-100

5101-165 OOE/JPL-1012-53 JPL Publ. #81-30

FSA PUBLIC DOCUMENTS

Moore, D. M. Karch 1, 1980

Christensen, E.

JPL April 1980

Proposed Method for Determining the Thickness of Glass in Solar Collector Panels

Electricity from Photovoltaic Solar Cells/LSA Project/As displayed at Congressional Hearings February 1980

Progress Report 15 for the period December 1979 to April 1980 and Proceedings of the 15th Project Intregration Meeting

Chamberlain/Aster/ SAMICS Cost Account Catalog/Version 4 Firnett April 21, 1980

Christensen, E. June 1980

Firnett, P. J. November 17, 1980

Aster/Chamberlain Hiller/Firnett November 17, 1980

National Photovoltaic Progam/Electrical Power from Solar Cells

Improved Price Estimation Guidelines (IPEG) Computer Program User's Guide Release 2

Improved Price Estimation Guidelines (IPEG) Design Document Release 2

Chamberlain/Firnett Improved Price Estimation Guidelines Miller (IPEG) Computer Program Source Code November 17, 1980 Release 2

Project Office

Wilson, A. H. June 15, 1981

65

Progress Report 16 for the period April to September 1980 and Proceedings of the 16th Project Integration Meeting

Low-Cost Solar Array Structure Development

D D 0 D 0 D D D D D 0

5101-166 DOE/JPL-1012-52 JPL Publ. #81-12

5101-169 DOE/JPL-1012-50 JPL Publ. #81-1

5101-170

5101-171 OOE/JPL-1012-55 JPL Publ. #81-37

5101-172 DOE/JPL-1012-54 JPL Publ. #81-35

5101-173 DOE/JPL-1012-62 JPL Publ. #81-111

5101-175 DOE/JPL-1012-61 JPL Publ. #81-112

5101-176 OOE/JPL-1012-56 JPL Publ. #81-64

5101-177 DOE/JPL-1012-60 JPL Publ. #81-102

5101-178C

FSA PUBLIC DOCUMENTS

Jaffe, Peter December 30, 1980

Seaman, c. H. January 15, 1981

Engineering Area Kay 20, 1980

Kokashi/Kachare Karch 15, 1981

LSA Project

Kon/Moore/Ross March 1, 1982

Mokashi, A. R. December 15, 1981

Daud/Cheng November 1, 1981

Carroll/Coulbert Cuddihy/Gupta Liang June 1, 1982

LSA Project July 1981

66

LSA Field Test Annual Report August 1979-August 1980

The Correction for Spectral Mismatch Effects on the Calibration of a Solar Cell When Using A Solar Simulator

Flat-Plate Photovoltaic Module & Array Circuit Design Optimization Workshop Proceedings-May 19 & 20, 1980

Sensitivity Analysis of the Add-On Price Estimate for the Edge-Defined Film-Fed Growth Process

Progress Report 17 for the Period September 1980 to February 1981 and Proceedings of the 17th Project Integration Meeting

Interconnect Fatigue Design for Terrestrial Photovoltaic Modules

Sensitivity Analysis of the Add-on Price Estimate for the Silicon Web Growth Process

Measurement of Surface Recombination Velocity for Silicon Solar Cells Using a Scanning Electron Microscope with Pulsed Beam

Photovoltaic Module Encapsulation Design and Materials Selection: Volume I

Electricity form Photovoltaic Solar Cells-Low Cost Solar Array Project As Displayed at the 15th Phot9voltaic Specialist Conference-May 1981 Revised for Project Integration Meeting

D D Fl u

D D D D D

5101-186 DOE/JPL-1012-58 JPL Publ. #81-94

5101-187 DOE/JPL-1012-66 JPL Publ. #82-9

5101-188 DOE/JPL-1012-63 JPL Publ. #81-118

5101-189 DOE/JPL-1012-57 JPL Publ. #81-76

5101-194 DOE/JPL-1012-67 JPL Publ. #82-11

5101-197 DOE/JPL-1012-59 JPL Publ. #81-99

5101-201 DOE/JPL-1012-69 JPL Publ. #82-28

5101-202 DOE/JPL-1012-79 JPL Publ. #82-109

5101-203 DOE/JPL/1012-65 JPL Publ. #82-3

5101-204 DOE/JPL-1012-68 JPL Publ. #82-20

FSA PUBLIC DOCUMENTS

PROJECT OFFICE

JPL February 1, 1982

Burger, D. R. January 15, 1982

K. A. Yamakawa September 1, 1981

PROJECT OFFICE

Jaffe/Weaver/Lee December 15, 1981

Wen, L. March 1982

Gonzalez, C. C. December 15, 1982

Von Roos, o. H. February 15, 1982

JPL March 1, 1982

67

Progress Report 18 for the Period February to July 1981 and Proceedings of the 18th Project Integration Meeting.

Proceedings of the Low-Cost Solar Array Wafering Workshop (8 - 10 June 1981, The The Pointe, Phoenix, Arizona)

Vacuum Lamination of Photovoltaic Modules

The Effects of Impurities on the Performance of Silicon Solar Cells

Progress Report 19 for the Period July to November 1981 and Proceedings of the 19th Project Integration Meeting

FSA Field Test Annual Report August 1980-August 1981

An Investigation of the Effect of Wind Cooling on Photovoltaic Arrays

Photovoltaic Array-Power Conditioner Interface Characteristics

Mathematical Analysis of the Photovoltage Decay (PVD} Method for Minority Carrier Lifetime Keasureaents

Introduction to SIKRANS Simulation of Research and Development Project

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5101-207 DOE/JPL-1012-70 JPL Puhl. #82-35

5101-209 DOE/JPL-1012-71 JPL Publ. 1#82-48

5101-210 DOE/JPL-1012-72 JPL Puhl. #82-42

5101-211 DOE/JPL-1012-73 JPL Publ. 1#82-52

5101-212 OOE/JPL-1012-74 JPL Puhl. #82-65

5101-214 DOE/JPL-1012-75 JPL Publ. #82-73

5101-215 OOE/JPL-1012-85 JPL. Puhl. #83-29

5101-216 DOE/JPL-1012-77 JPL Publ. #82-81

5101-217 DOE/JPL-1012-78 JPL Publ. #182-82

5101-220 DOE/JPL-1012-87 JPL Publ. #83-35

FSA PUBLIC DOCUMENTS

JPL Advanced czochralski Silicon Growth September 15, 1982 Technology for Photovoltaic Modules

JPL Progress Report #20 for the Period November 1981 to April 1982 and Proceedings of the 20th Project Integration Meeting

Liang/Gupta Photothermal Characterization of Encapsulant Materials for Photovoltaic Modules

Frichland/Repar April 6, 1982

Mokashi, A. R. September 15, 1982

Smokler, M. I. September 1, 1982

Maxwell, H.G. April 15, 1983

Cuddihy, E. September 1, 1982

Cockrum, R. H. September 15, 1982

Cuddihy, E. April 15, 1983

68

Experimental Evaluation of the Battelle Accelerated Test Design for the Solar Array at Head, Nebraska

Price Estimates for the Production of Wafers from Silicon Ingots

User Handbook for Block IV Siicon Solar Cell Modules

FSA Field Test Report 1980-1982

Photovoltaic Module Encapsulation Design and Materials Selection, Volume I (Abridged)

A System for Measuring Thermal Activation Energy Levels in Silicon by Thermally Stimulated Capacitance

Applications of Ethylene Vinyl Acetate as an Encapsulation Material for Terrestrial Photovoltaic Modules

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5101-221 DOE/JPL-1012-76 JPL Puhl. #82-79

5101-222 DOE/JPL-1012-88 JPL Publ. #83-48

5101-224 DOE/JPL-1012-84 JPL Publ. #83-27

5101-226 DOE/JPL-1012-83 JPL Publ. #83-22

5101-228 DOE/JPL-1012-81 JPL Publ. #83-13

5101-230 DOE/JPL-1012-86 JPL Publ. #83-32

5101-231 DOE/JPL-1012-89 JPL Pub. #83-52

5101-232 DOE/JPL-1012-91 JPL Pub. t#83-86

5101-233 DOE/JPL-;1012-90 JPL Pub. #83-87

5101-237 DOE/JPL-1012-97 JPL Pub. ##84-34

FSA PUBLIC DOCUMENTS

JPL September 15, 1982

JPL

Coulbert, C. April 1, 1983

Burger, D.R. Jan. 15, 1983

JPL February, 1983

Liang, R.H. May 1, 1983

FSA Project June 1, 1983

Coulter/Cuddihy Plueddeman November 15, 1983

Cheng/Shyu/Stika Daud/Crotty November 15, 1983

Cuddihy, E. June 1, 1984

69

Summary of Flat-Plate Solar Array Project Documentation, Abstracts of Published Documents, 1975 to June 1982

Progress Report 21 for the Period April 1982 to January 1983 and Proceedings of the 21st Project Integration Meeting

The Application of Encapsulation Material Stability Data to Photovoltaic Module Life Assessment.

Development of a Large Low-Cost Double-Chamber Vacuum Laminator

Proceedings of the Flat-Plate Solar Array Workshop on the Science of Silicon Material Preparation (August 23, 24, 25, The Pointe, Phoenix, Ar-izona)

Handbook of Photothermal Test Data on Encapsulant Materials

Proceedings of the Flat-Plate Solar Array Project Research Forum on Quantifying Degradation (December 6, 7, 8, 1982, Williamsburg, Virginia)

Chemical Bonding Technology for Terrestrial Photovoltaic Modules status to February, 1983

Characterization of Grain Boundaries in Silicon

Photovoltaic Module Encapsulation Design and Materials Selection: Volume II

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5101-238 DOE/JPL-1012-95 JPL Pub. #84-23

5101-239 DOE/JPL-1012-92 JPL Pub. #83-93

5101-242 DOE/JPL-1012-94 JPL Pub. #84-2

5101-244 DOE/JPL-1012-96 JPL Pub. #84-24

5101-246 DOE/JPL-1012-93 JPL Pub. #83-94

5101-247 DOE/JPL-1012-98 JPL Pub. #84-44

5101-250 DOE/JPL-1012-99 JPL Pub. #84-47

FSA PUBLIC DOCUMENTS

FSA Project April 15, 1984

FSA Project November 15, 1983

FSA Project

R. Lutwack February 1, 1984

Reiter, L. J. November 15, 1983

FSA Project

FSA Project

70

Proceedings of the Flat-Plate Solar Array Project Research Forum on the High-Speed Growth and Characterization of Crystals for Solar Cells (July 25, 26, and 27, 1983, at Port St. Lucie, Florida) PLEASE CONTACT FSA PROJECT OFFICE FOR COPIES OF THIS DOCUMENT

Proceedings of the Flat-Plate Solar Array Project Research Forum on Photovoltaic Metallization Systems (March 16, 17, 18, 1983, at Pine Mountain, Georgia) PLEASE CON~ACT FSA PROJECT OFFICE FOR COPIES OF THIS DOCUMENT

Progress Report 22 for the Period January to September 1983 and Proceedings of the 22nd Project Integration Meeting

A Review of the Silicon Material Task

Probabilistic Analysis of Silicon Cost

Proceedings of the Flat-Plate Solar Array Project Research Forum on The Design of Flat-Plate Photovoltaic Arrays for Central Stations (December 5, 6, 7, 8, 1983, at Sacramento, California) PLEASE CONTACT FSA PROJECT OFFICE FOR COPIES OF THIS DOCUMENT

Progress Report 23 for the Period September 1983 to March 1984 and Proceedings of the 23rd Project Integration Meeting

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FSA PUBLIC DOCUMENTS

5101-251 DOE/JPL-1012-102 JPL Pub. •84- 72

5101-254 DOE/JPL-1012-100 JPL Pub. #84-52

Cuddihy/Willis November 15, 1984

Weaver/Lee/Meyer Runkle August 15, 1984

Antisoiling Technology: Theories of Surface Soiling and Performance of Antisoiling Surface Coatings

FSA Field Test Annual Report; August 1981 - January 1984

Please contact the FSA Data Center for those documents which do not carry a DOE/JPL number. (818) 577-9519 or 577-9520

71

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