MIT Lincoln Laboratory Verghese_AFRL101906-1 S. Verghese 10/19/06 Avalanche Photodiodes for 3-D LADAR and Communications* S. Verghese *This work was sponsored

MIT Lincoln Laboratory

Verghese_AFRL101906-1S. Verghese 10/19/06

Avalanche Photodiodes for 3-D LADAR and Communications*

S. Verghese

*This work was sponsored by the National Aeronautics and Space Administration (NASA) Goddard under the Department of the Air Force contract number FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Government.

MIT Lincoln LaboratoryVerghese_AFRL101906-2S. Verghese 10/19/06

Key Technical Contributors

• InP APDs

• CMOS ROIC

K. A. McIntosh J. P. Donnelly E. K. Duerr D. C. Oakley

G. M. Smith L. J. Mahoney P. I. Hopman C. Vineis

K. E. Jensen K. M. Molvar J. Aversa S. H. Groves

J. M. Mahan Z.-L. Liau C. D. Parker A. Napoleone

F. J. O’Donnell M. P. Kesler E. A. Dauler K. Carbonari

T. J. McIver P. Chapnik J. E. Funk S. A. Hamilton

L. Retherford G. Lambert D. Chapman D. C. Shaver

E. J. Ouellette D. M. Cohen J. P. Frechette C. N. Stevenson

J. B. Glettler B. F. Aull M. Renzi S. Verghese


Geiger-Mode: Photon-to-Digital Conversion

• Single-photon sensitivity

• Low dark-count rate

• All-digital readout circuit

• Compact and low power

• Sub-ns timing

APD

Digitaltimingcircuit

Digitally encoded photon time-stamp

photon

Pixel circuit

Polyimidepassivation

4 mLensletArray

InP APDArray

CMOSROIC

InP

Su

bs

tra

te

InG

aA

sP a

bso

rber

InP

mu

ltip

lie

r

InP APD

Device Profile

Photons


InP Avalanche Photodiodes

• Introduction

• Applications

• APD Figures of Merit

• Read-Out Integrated Circuit (ROIC)

• Summary


JIGSAW: Short-range 3-D LADAR imaging*

OrganicAir Vehicle

• Locate and identify obscured targets within given area of 20 x 20 m

• Use angular diversity to maximize penetration of foliage

• Register and visualize data

• ID target from single pass

(100-m altitude)

Phase 1 OAV Ladar System

Mass: 0.34 kgVolume: 3 litersPower: 5 W

*Slide courtesy Dr. Rich Marino


RF Deep-Space Links are Power Limited

Neptu

ne

Uranu

s

Saturn

Jupi

ter

PlutoGEO Moon

dB GEO Link (R2)

0 10 20 30 40 50 60 70 80 90 100 110

36

000

km

VenusMercury

Mars

40

0 m

illi

on

km

34-m Receive Antenna, NASA Deep-Space Network

3-m Transmit Antenna,Mars Reconnaissance Orbiter

Mars Reconnaissance Orbiter

• Launched 8/05

• Ka-band, 32 GHz

• 35-W transmit power

• Data rates up to 2.8 Mbit/s


Neptu

ne

Uranu

s

Saturn

Jupi

ter

PlutoGEO Moon

36

000

km

VenusMercury

Mars

40

0 m

illi

on

km

5-m Receive Aperture,Hale Telescope

0.3-m Transmit Aperture,Mars Telecommunications Orbiter

Mars Laser CommunicationsDemonstration

• 1.06 m, optical carrier

• 5-W transmit power

• Data rates up to 46 Mbit/s

0 10 20 30 40 50 60 70 80 90 100 110

dB GEO Link (R2)

Optical Deep-Space Links are Photon Starved



• Introduction

• Applications


– Photon Detection Efficiency (PDE)

– Reset Time

– Dark Count Rate (DCR)


• Summary


PDE and Reset Time: 1.06 m APDs

Hermetic Package

Figures of Merit:

• Probability of Detection (45%)• Reset Time (1.6 s)• Dark Count Rate (20 kHz)


4 mLensletArray

InP APDArray

CMOSROIC

InP

Su

bs

tra

te

InG

aA

sP a

bso

rber

InP

mu

ltip

lie

r

InP APD

Device Profile

Photons


101 102 103 104 105-3

-2

-1

0

1x1 APD array 2x2 APD array 4x4 APD array 8x8 APD array

Blo

ckin

g L

oss

[d

B]

R (photon rate) [KHz]

APD Blocking Losses

Reset time: 1sDark count rate: 10KHz

Mitigating Reset-Time Blinding

2x2 Array

Photon rate per APD reduced by 4

1 2

3 4

10% signal loss fromsignal-flux blockage

• III-V Geiger-mode APDs must rest after firing for a hold-off time (tho), also called the Reset Time.

• Spreading the signal over many pixels reduces the odds of a signal photon striking a blinded pixel

• Eliminating the trapped carriers requires dramatic materials improvements

10 MHz

V bias Breakdown voltage

Rea

do

ut

tho

APD fire

thotho thotho

Breakdown voltage

Trapped Carriers

APD fire

V bias

Trapped Carriers

tho

V bias

APD fire

Trapped Carriers

Breakdown voltage

V bias Breakdown voltage

Rea

do

ut

tho

APD fire

thotho thotho

Breakdown voltage

Trapped Carriers

APD fire

V bias

Trapped Carriers

tho

V bias

APD fire

Trapped Carriers

Breakdown voltage

Blinded

Observing

APD pixel #2 (time-history)

TrappedCarriers


Hermetic Package

Figures of Merit:

• Probability of Detection (45%)• Reset Time (1.6 s)• Dark Count Rate (20 kHz)


4 mLensletArray

InP APDArray

CMOSROIC

InP

Su

bs

tra

te

InG

aA

sP a

bso

rber

InP

mu

ltip

lie

r

InP APD

Device Profile

Photons

Dark Count Rate: 1.06 m APDs


30 25 20 15 10 5 00

50

100

150

200

250

300

350

400

0.0

0.2

0.4

0.6

0.8

1.0

Ph

oto

n D

ete

cti

on

Eff

icie

nc

y

D

ark

Co

un

t R

ate

[k

Hz]

APD Photo Sensitive Diameter m]

Dark Count Rate

Photon Detection Efficiency

APD Diameter Optimization

Goal: Use APD diameter for minimum DCR and max PDE

PDE rolloff due to microlens coupling inefficiency

Desired Size


10um

10um

8um

8um

13um

CCS136 CCS192 CCS214 CCS268 CCS2681

10

100

1000

4.0V overbias 5.0V overbias

DC

R (

kHz)

Measured Results (1.06-um APDs)

Requirements (@PDR) DCR PDE Reset

Best Device (ccs136)(10C,10um diameter)

65 kHz 47% 1.6 us

DCR < 30kHz at T = 300K (13um diameter APD)

Dark-Count Rate (DCR)

Room Temperature

Effective device diameter

4 50

10

20

30

0.40

0.45

0.50

0.55

0.60

PD

E

Dark Count Rate

DC

R [

kH

z]

Overbias [V]

Photon Detection Efficiency

Photon Detection Efficiency (PDE)

Overbias (V)

PDE with latest devices 50%

MOCVD-growth run

-10 -5 0 5 100.0

0.2

0.4

0.6

0.8

1.0

Position [m]

Photo-response Profile

Then:

Now:


APD Performance (1.06 & 1.55 um)Expected

Near-term GOAL

Near-term GOAL

Jan. 2006 Performance

DCR X Reset = 0.12

Zero-bkgnd Blockage: -0.5

Microlens loss: -1.5 dB

DCR X Reset = 0.03

Zero-bkgnd Blockage: -0.14

Microlens loss: -1.5 dB

Yb Fiber Amplifier compatible ( = 1.06 m)

Parameter Current Device Performance

Comments

PDE (5V overbias) 45% 20 um diam APDs (15 um-photoactive)

DCR (5V, +25oC) 20 kHz 20 um diam APDs

Reset Time (+10oC) 1.6 us On CMOS ROIC

Parameter Current Device Performance

Comments

PDE (5V overbias) 40% 20 um diam APDs (15 um-photoactive)

DCR (5V, -33oC) 20 kHz 20 um diam APDs

Reset Time (-33oC) 6.0 us On CMOS ROIC

InGaAsP/InP Epitaxy InGaAs/InP Epitaxy

Jan. 2006 Performance

Er Fiber Amplifier compatible ( = 1.55 m)

Higher PDE and reduced lossHigher PDE and reduced loss

0.016

-0.07dB

-1.0 dB

0.06

-0.25 dB

-1.0 dB

10 kHz

55%

10 kHz

50%


LDES Receiver Test Bed

Avalanche Photodiodes:Single-photon arrival timing

Receiver Sync Board:Clock synchronizationFrame synchronizationAPD ROIC emulation

Receiver Workstation:PPM DemodulationTurbo DecodingDisplay and Diagnostics


Current development in LADAR APDs

• Increased Array Size

• Reduced Pixel Size

• Enhanced Processing, Functionality

• Spectral Coverage

Metric Requirement• Uniformity

256x64, 50 m

• 3D Integration

• Fast Reset, Counting, Low Jitter, Caching

• Other Materials

InP

5V SOI

2V SOICarrier wafer



• Introduction

• Applications


– Photon Detection Efficiency (PDE)

– Reset Time

– Dark Count Rate (DCR)


• Summary


3D Ladar Imaging at 1.06 m

• 1.064m Nd:YAG chip laser

• InGaAsP/InP APDs on CMOS

Detection probabilitycolor code

Rotatable 3D Image Conventional LADAR Array Concept:

• All pixels armed synchronously

• Low duty cycle (PRF dependent)

Observing (< 1us)

(Range Gate)

32

x3

2 G

M-A

PD

Arr

ay

1

2

3

4

Arr

ay R

ead

ou

t

Arr

ay R

ead

ou

t

Blinded (> 50us)


8x

8 G

M-A

PD

Arr

ay

1

2

3

4

Laser Communications at 1.06 m

• 1.06 m Yb-doped fiber amplifier

• InGaAsP/InP APDs on CMOS

Mars LaserCom

• All pixels armed asynchronously

• 100% duty cycle

Observing

MTO/MLT(cancelled)

LDES

OpticalDownlink

LaserCom Array Concept:


1 2 3 4 5 6 7 8

16 la

nes

@ 5

12 M

b/s

Frame-Store

Clock Gen

8x8 Array

TS_CLK1024 MHz

128-512 MHz CLKDiags

8 la

nes

@ 1

28-5

12 M

b/s

Mars LaserCom ROIC Block Diagram

• Single-clock input (TS_CLK)• Modest area and power consumption• User friendly (FPGA compatible, self-test, etc)

• Arm and disarm APD• Record time of photon arrival• Record location of photon arrival

ROIC Requirements: Design Guidelines:

APD

Digitaltimingcircuit

Encodedphotonarrival time

Lensletarray

ROIC Pixel Circuit

APDarray

CMOSROIC

Photons

~ 2 Vpp


1 2 3 4 5 6 7 8

16 la

nes

@ 5

12 M

b/s

Frame-Store

Clock Gen

8x8 Array

TS_CLK1024 MHz

128-512 MHz CLKDiags

8 la

nes

@ 1

28-5

12 M

b/s

Mars LaserCom Read-Out IC

• Mates to 8x8 InP APD array

• Rev2 chip: operating in test-bed

Pixel Cell Layout

Definition of Chip Architecture

Wafer-Probe Test Structures

MLCD ROIC Mirrored Copy

0.35-um CMOS Fab

Tested on Logic Analyzer at 311 MHz

Packaging and Test Verification (Jan ‘05) Simulations and Layout

DATA_I DATA_O

RE

SE

T

RRQBUS_I RRQBUS_O1

Pixel 7

TS_CLK

RESET8 MHz (derived on-chip from TS_CLK)

622 MHz (off-chip)

63

00000010

Data Off Chip

DATA_I DATA_O

RE

SE

T

RRQBUS_I RRQBUS_O0

Pixel 6

FIRED

(Time-slot 6

3)

DATA_I DATA_O

RE

SE

T

RRQBUS_I RRQBUS_O0

Pixel 8

TS

_C

LK

TS

_C

LK

TS

_C

LK

7 bits wide

DATA_I DATA_O

RE

SE

T

RRQBUS_I RRQBUS_O1

Pixel 7

TS_CLK

RESET8 MHz (derived on-chip from TS_CLK)

622 MHz (off-chip)

63

00000010

Data Off Chip

DATA_I DATA_O

RE

SE

T

RRQBUS_I RRQBUS_O0

Pixel 6

FIRED

(Time-slot 6

3)

DATA_I DATA_O

RE

SE

T

RRQBUS_I RRQBUS_O0

Pixel 8

TS

_C

LK

TS

_C

LK

TS

_C

LK

7 bits wide

Concept for Asynchronous APD Pixels (Jan ‘04)

BYPASSED

BYPASSED


Packaged LaserCom ROIC

Alumina InterposerAlumina Interposer

CMOS ROICCMOS ROIC

Package (lid removed)Package (lid removed)

0402 Cap0402 Cap

LVCMOS — LVDSTranslator Chip LVCMOS — LVDSTranslator Chip

0.5 in

2 in


Micro Lens Array Alignment

• APD active area (small ~10 um diam.)

• Demonstrated < 2um alignment error

• Submicron alignment in development

150 um 150 um

100 um

pitch

GaP InP

n1 n2

150 um 150 um

100 um

pitch

GaP InP

n1 n2

GaP Lens

Ray-trace

PhotoAbsorber

InP APDAPDarray

CMOSROIC

Lenslet array: 8x8 100-m pitch

CMOS ROICCMOS ROIC

Alumina InterposerAlumina Interposer

APD with u-lensAPD with u-lens

Active Alignment Diodes

Active Alignment Diodes I

xyz-stage APD

u-lens

1.064 um collimated source

I

xyz-stage APD

u-lens

1.064 um collimated source

Active Alignment for Low Loss

Microlens-Alignment Challenge:


Package for Mars LaserCom ROIC

• MIT/LL design; Kyocera fab

• Hermetic with integrated TEC

• 70 high-speed pins (< 6 GHz simulated)

APD Module

CuW Heat sink

Bezel

Alumina

APD/ROIC

KovarHousing

80% Ar20% He

Sapphire Window

TEC

MLA

Heat sink attached to cold plate through cold strap

APD Module

CuW Heat sink

Bezel

Alumina

APD/ROIC

KovarHousing

80% Ar20% He

Sapphire Window

TEC

MLA

APD Module

CuW Heat sink

Bezel

Alumina

APD/ROIC

KovarHousing

80% Ar20% He

Sapphire Window

TEC

MLA

Heat sink attached to cold plate through cold strap

Kovar housing

Ceramic package

CuWheatsink

Kyocera (160 PGA) MLCD Package w/ Rev2 ROIC & APD

160-pin Pin-Grid-Array Package


Current Development in APD Read-Out ICs

10 kHz 100 kHz 1000 kHz

Pixel refresh rate or PRF (Hz)

Arr

ay s

ize

(pix

els)

100

1000

10,000

100,000

32x32

128x32

256x64

8x8

USD_32x32

10 9 photons/sec10 7 photons/sec10 5 ph/sec

Saturation Flux = 10 11 photons/sec

NbN?

• Low PRF (<< 1 MHz)– High peak power– Background rejection– Large pixel count– Most LADAR applications

• High PRF (> 1 MHz) – Average power (energy on

target)– Modest background rejection– Smaller pixel count– Most LaserCom applications

PRF = Pulse Repetition FrequencyROIC = Read-Out Integrated Circuit

Two styles of ROIC design: Fabricated ROIC Planned ROIC

Mapping LADARMapping LADAR

Other LADAROther LADAR

LaserComLaserCom


Dual 128x32 ROICs in MLCD package

• Two overlapping 128x32s (50-um pitch)


InP APDs: Summary

• We built and demonstrated integrated InP APD arrays for LaserCom and LADAR

– InGaAsP/InP for 1.06-um wavelength

– InGaAs for 1.55-um wavelength (less mature)

• Current focus:

– Increasing Photon Detection Efficiency

– Decreasing Dark Count Rate

• Hybrid-assembly of InP arrays with Si CMOS enables:

– High fill-factor photon counters (up to 4kpixels)

– Compact, low-power sensor (plugs into a pc board)

MIT Lincoln Laboratory

Verghese_AFRL101906-28S. Verghese 10/19/06

End

S. Verghese


Receiver Development Example (MarsCom)

Physics

System Analysis

Mars

InGaAs Growth

InP waferfabrication

APD design& modeling

MLCD Program Office

Candell, BorosonLDES

1.06-um test-bed1.55-um test-bed

Wafer-probePackage, TestCMOS, PCB

Mar

s L

aser

Co

m—

LD

ES

Div8

G83

G83

Div6,9

Hopman, Hamilton

Duerr, McIntosh, Hopman

SmithDonnelly

Epi Vendor

PhotodiodeVendor

Contract Mfg

System Integrator

IndustryMIT-LL

Oakley, Vineis

Documents

MIT Lincoln Laboratory Verghese_AFRL101906-1 S. Verghese 10/19/06 Avalanche Photodiodes for 3-D LADAR and Communications* S. Verghese *This work was sponsored