Isotype heterojunction in HgCdTe photodiodes

Results of a study of the optical and electrical performance of P-on-n HgCdTe photodiode configuration are presented. The effect of doping profile and heterostructure contacts with wide gap region on the photodiode parameters is solved by forward-condition steady-state analysis. An isotype heterojunction, a high/low junction or very heavily doped high quality p-type material is required to achieve competitive performance from this device architecture in the diffusion limited temperature regime. It is shown that the isotype heterojunctions have the advantages over a high/low homojunctions for IR detectors. The wide gap region has low thermal generation rates of carriers and it also isolates the active region of the device from carrier generation at the contacts. Results obtained from computer simulations were found to be in qualitative agreement with previous experimental data on HgCdTe photodiodes.