Charge-limited domains in gallium-arsenide avalanche diodes

An analysis of the high-efficiency mode of operation of gallium-arsenide avalanche diodes is presented. The concept of a charge-limited domain is introduced, and it is shown that the occurrence of this domain effectively increases the velocity of the travelling charges. This velocity increase occurs at a point roughly midway through the transit time, and causes an increase in the induced particle current at that time. This effect, coupled with the effects of depletion-layer-width modulation, has an important bearing on the observed high efficiency of nonpunchedthrough ‘clump’ and ‘hi-lo’ gallium-arsenide structures.