A model for the trap-assisted tunneling mechanism in diffused n-p and implanted n+-p HgCdTe photodiodes

A theoretical model for the trap-assisted tunneling process in diffused n-on-p and implanted n⁺-on-p HgCdTe photodiodes is presented. The model describes the connection between the leakage current associated with the traps and the trap characteristics: concentration, energy level, and capture cross sections. It was observed that the above two types of diodes differ in the voltage dependence of the trap-assisted tunneling current and dynamic resistance. The model takes this difference into account and offers an explanation of the phenomenon. The good fit between measured and calculated DC characteristics of the photodiodes (for medium and high reverse bias and for temperatures from 65 to 140 K) supports the validity of the model