Three-dimensional limitations on space-charge growth in transferred-electron devices

Abstract

The influence of diffusion and the lateral dimensions on the growth of space-charge non-uniformities from random electron density fluctuations is calculated for a negative differential resistance material. The effect of these considerations on the performance of some transferred-electron devices is then presented. The f.m. noise performance of Gunn oscillators was overestimated by 13 dB in a previous calculation, and the allowable space charge growth in limited space-charge accumulation oscillators was underestimated. It is concluded that fully formed domains do not exist in uniform short (similar, equals 10 μm) Gunn effect devices.