Model for trap filling and avalanche breakdown in semi-insulating Fe:InP

Abstract
A self-consistent two-carrier numerical model for steady-state current flow in n -semi-insulating- n InP structures allows the treatment of avalanche breakdown in addition to trap filling. Band-to-band impact ionization is included as a source term in the continuity equations. Carrier diffusion, nonlinear velocity field characteristics, and Shockley-Read-Hall recombination through the traps are also included, and the effects of each on the field and trapped carrier distributions are calculated. (The progress of trap filling predicted by the traditional drift-only theory is also calculated.) With impact ionization, hole accumulation near the cathode redistributes the space charge and contributes to positive feedback for avalanche breakdown. The model predictions are consistent with experimentally observed catastrophic breakdown and allow the development of design guidelines for avoiding device failure.