1.02 IEEE Two of the device families are formed by

planar diffusion techniques, and the re- maining two are fabricated using a combina- tion of the epitaxial growth and the diffusion techniques. The versatility of epitaxial techniques in forming silicon integrated circuits is used to great advantage. Ex- amples of silicon integrated circuits fabri- cated by three of these processes are shown and discussed, in light of the various parasitics affecting circuit performance. These circuits include, 1) a bistable multi- vibrator (flip-flop), 2) a digital logic circuit performing either the KOT-AND function, or the NOT-OR function, and 3 ) a 12- megacycle linear amplifier.

It is shown that a combination of the epitaxial growth and diffusion techniques present a flexible system for the formation of silicon integrated circuits. Either type of isolation scheme may be used a t low frequencies, but circuit performance above 100 megacycles requires the parasitic-free resistive isolation method.

5) Determination of Temperature Pro- files in Microcircuits-M. Walker, J . Roschen, and E. Schlegel, Philco Corp., Landsdale, Pa.

Circuit reliability and performance, par- ticularly in microcircuits, are affected by temperature; therefore, a knowledge of the heat transfer paths and temperature gradients and hot spots are of prime importance to proper design specifications and to efficient performance of microcircuits.

The method of thermal mapping de- scribed in this paper involves a direct and rapid infrared scanning technique. The "heart" of the system is a photosensitive element of single crystal indium antimonide with a long wavelength cut off near six microns. The method has been found to be satisfactory in generating isothermal pat- terns in tantalum microcircuits from 50" C to >250" C. Hot spots 1.3 mil in diameter are readily detec~ted.

Isothermal patterns of various geometries will be shown and used to examine the design adequacy for different load condi- tions. The effect of sheet resistivity and individual resistive thin film layout patterns on temperature profiles is described.

Operating stability and life data of thin film resistive tantalum patterns as a func- ticn of maximum temperature is presented. Immediate determination of power handling capability through the knowledge of the maximum temperature is possible without resorting to the slow procedure of life t.esting for every new condition of operation.

Isothermal profiles in solid silicon circuits are also presented and discussed.

6 ) Analysis of the Simultaneous Fabrica- tion of Unipolar and Bipolar Transis- tors in a Functional Block--. K. Yzc, H . C. L in , and -M. J . Geisler,

Westinghouse Central Laboratories, Pittsburgh, Pa.

A monolithic functional block containing both unipolar and bipolar transistors was described by K. K. Yu and L. Pollack at the 1961 PGED Meeting. Both unipolar and bipolar transistor structures were fabricated simultaneously by means of double dif-

TRANSACTION8 ON ELECTRON DEVICES March fusion, as for conventional planar tran- sistors. However, the presence of the unipolar transistors imposes some additional requirements on the controlling parameters. This paper analyzes the problems involved and discusses the compromises and criteria in design.

For the unipolar transistors the major considerations are the pinch-off voltage, pinch-off current, the transconductance and the breakdown voltage. For the bipolar transistors, on the other hand, the principal characteristics are the gain and breakdown voltage. In both cases the controlling parameters for these characteristics are the surface concentration, the shape of the impurity profiles, junction depth, etc. The paper analyzes the requirements of these two active devices in the terms of ex- ponential, complementary error function and Gaussian distributions and points the way to an optimum design for both. The analytical results check well with experi- ments.

7) Nanowatt Devices-W. W. Gaertner, C B S Laboratories, Stamford, Conn.

Present emphasis in device research is placed on higher speed and higher power output. This is partly a consequence of the fact that the majority of present infor- mation-handling schemes are based on serial processes, and data processing ca- pacity is proportional to the speed of the individual devices. On the other hand there is a large area of present and potential problems where information would better be processed in parallel channels or in arbitrary combinations of parallel and serial paths. The latter approach to data handling calls for systems with a very large number of devices, most of them active or a t least switchable. This number may be in the high millions. Under these circum- stances power consumption and size become of greatest importance.

This paper therefore investigates the question of the lower limit for the power consumption of active solid-state devices, or, in other words: Utilizing known physical principles, for how low a power consumption can one design and fabricate active devices? As an introduction the paper briefly describes the design, fabrication and per- formance of integrated amplifier and digital function blocks operating a t supply power levels of 1 to 10 microwatts. Then the paper analyzes the problems encountered if the supply power is lowered into the range between 1 nanowatt and 3 microwatt. These are a) basic physical limitations, b) noise, e) speed, and d ) technological limitations (pointing to potentially profit- able areas of research). The results of experiments with some exploratory devices are described and the conclusion is drawn that the next few years will see the 1 to 1000 nanowatt supply power range opened up for practical device applications.

8) Stray Capacitance in Thin Film

Missiles dk Space Co., Sunnyvale, Calif. Circuits-W. W. Happ, Lockheed

The interelectrode capacitance in film- type circuits becomes a critical design

limitation as dimensions decrease and as substrates of high dielectric constants are developed. Design charts and engineering approximations are presented and illustrated by evaluating the effect of stray capacitance on a completed film-type IF amplifier circuit.

9) Integrated, Unijunction Transistor Oscillators*+. Hachtel and D. 0. Pederson, University of California, Berkeley.

The unijunction transistor (UJT) is being considered as the active element in an integrated harmonic oscillator realiza- tion. Necessary and sufficient conditions for oscillation in the harmonic mods have been determined. The dependence of the fre- quency constancy factor,

1 dwo wo dT __

on device temperature and bias-conditions is derived. These results depend on an ac perturbation analysis of the UJT. The analysis brings out in detail the known behavior of the UJT input port as a -R, L network at low frequencies. The input port is also shown to function as a fR, C net- work a t high frequencies. A natural reso- nance in the diffusion process a t medium frequencies is pointed out. An intrinsic UJT oscillator is proposed, based upon this resonance. Experimental work with commercially available UJT structures substantiates analytical results. Experi- mental studies of prototype oscillator circuits are used to design and integrated oscillator realization which is optimized with regard to temperature stability and waveform distortion.

Aeronautical Systems Divmion, Wright-Patterson * This research was supported in part by the

Air Force Base under contract AF 33(616)7553.

GENERAL SESSION SESSION 11

Chairman-R. W. SEARS Avalanche Multiplication Processors in Semiconductors-A. G. Chynoweth, Bell

Comparison of Hot Electrons and Related Telephone Laboratories, Murray Hill, N . J .

Amplifiers-J. L. Moll, Stanford Uni- versity, Stanford, Calif. Thermionic Energy Conversion- K. G. Hernqvist, R C A Laboratories, Princeton, N . J .

ENERGY CONVERSION DEVICES SESSION 111-A

Session Chairman, W. H. CLINGMAN Session Organizer, F. H. BOWER

1) Operating Characteristics of a Molten- Electrolyte Fuel Cell on Hydrocarbon and Hydrocarbon-Derived Fuels-C. 6. Peattie, I . Trachtenberg, J . K . Truitt, B. H. Barbee, J. F . Haejling,

A. H . White, Texas Imtruments Inc., T. Hooper, K . W. Kreiselmaier, and

Dallas, Tex.