Modeling of Dark Current in HgCdTe Infrared Detectors

This paper presents modeling work carried out using a finite-element modeling approach. The physical models implemented for HgCdTe infrared photodetectors are reviewed. In particular, generation–recombination models such as Shockley–Read–Hall through a trap level in a narrow bandgap and Auger recombination are included. These well-established models are described using widely published analytical expressions. This paper highlights both the unique set of trap parameters found to fit the dark current as a function of temperature and composition for mercury-vacancy p-type-doped photodiodes and their use in a finite-element code. An equivalent set of trap parameters is also proposed for indium n-type-doped material in a p-on-n photodiode simulated in three dimensions. Device simulations also include the impact ionization process to fine-tune the saturation dark current. Finally, excess dark current is also modeled with the help of nonlocal band-to-band tunneling, which requires no fitting parameters.