Fig. 1-SBE-4022 backward wave amplifier drive characteristic at 75 Gc.Fig. 2 4 u t p u t power vs frequency with constant input power for SBE-4022 operated as a superregenerative-BWA (top); and conventional BWA (bottom).appears to be no reason why such guns could not be utilized to provide a truly low noise SR-BWA.A major problem associated with silicon bipolar transistor performance a t low-current levels is the rapid falloff in gain which sets in for values of emitter current less than about 100 pa. Oxide passivated transistor technology has resulted in improved lowcurrent performance, but improvement is still needed for ultimate use in nanonatt circuitry. An important prerequisite, of course, for these transistors is extremely low leakage currents. In addition, other design parameters of base transport factor' and emitter injection efficiency* need to be optimized. The present investigation has been conducted to explore surface effects which strongly affect low-current alpha for doublediffused n-p-n transistors. The variation of base current I* which results in a decreaswas performed under a Westinghouse research p r e Manuscript received January 17. 1964. This work gram and also with some support from the Aeronautical Systems Division, Air Force Avionics Laboratory. Electronic Technology Division, W-PAFB. Ohio, under contract No. AF 33(616)-8449. 1 D. P. Kennedy and P. C. Murleu, 'Base region transport characteristics of a diffused transistor, I . Appl. Phys.. vol. 33. PP. 120-136; January: l%2. 2 D. P. Kennedy and P. C. Murley. Mmoritu carrier injection characteristics of the diffused emitter junction." IRE TRANS. ON ELECTRON DEVICES. VOl. ED-9, pp. 136142; March, 1%2.ing alpha a t low levels has been variously described334 in terms of separate recombination components at the surface, in the bulk emitter and base regions and in the emitter junction transition region. Iwersen, et aZ., ' have demonstrated the strong effect on transistor alpha a t low currents that results when the current associated with the edge of the emitter is minimized. This they accomplished with a guard ring emitter. A transverse potential gradient was developed in the emitter region in a direction such as to enhance injection toward the center of the emitter.The strong effects of the surface recombination component of base current have been seen empirically and are described in this communication. This has been accomplished by short heat treatments in various ambients at temperatures too low to modify the diffusion profiles.Transistors have resulted which exhibit values of ~F E as high as 1500 to 2000 when tested with IB= 1 microampere. These transistors have been examined for gain a t very low-current levels. It has been found particularly useful to plot IC and IB vs VEB, as did Iwersen, et aL4 The curves of Fig. 1 and Fig. 2 are representative, and show collector and base current as a function of emitter-base junction potential for standard process transistors and for transistors which have been annealed in hydrogen prior to metall...

Processing of p-channel silicon gate devices with a Si3N4/SiO2 gate dielectric is described in detail. Some attractive features of this particular process include polysilicon to silicon contacts, improved metal step coverage obtained with a glass flow anneal, low fast surface-state density for good 1/f noise performance, and high parasitic field threshold voltages obtained by ion implantation of arsenic.* Electrochemical Society Active Member.

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