Soft-threshold lucky drift theory of impact ionisation in semiconductors

摘要

Arguments are presented for the existence of a soft threshold to impact ionisation in GaAs and other related semiconductors. A soft-threshold factor is introduced into the theory of lucky drift and the results are applied to some major semiconductors. Excellent fit of theory to experiment is obtained, which confirms that the thresholds are indeed soft. Soft-threshold factors and new mean free paths are obtained for Ge, Si, GaAs, InP and GaP. The mean free paths are shown to obey a simple law. The results for GaAs are applied to the case of multilayer APD. It is shown that excellent agreement with the results of Capasso et al. (1982) are obtained, even with a 60:40 division of band edge discontinuity.