Calculated performance of an Auger-suppressed unipolar HgCdTe photodetector for high temperature operation

The performance of leading HgCdTe p-n junction infrared (IR) device technology is limited by thermal generation-recombination (G-R) mechanisms and material processing challenges associated with achieving low, controllable in-situ p-type doping using molecular beam epitaxy (MBE) growth techniques. These aspects are addressed in the proposed hybrid HgCdTe NB nu N structure which relies on band gap engineered layers to suppress Shockley-Read-Hall (SRH) and Auger G-R processes contributing to performance degradation. The unipolar NB nu N architecture provides the desired advantages of a simplified fabrication process, eliminating p-type doping requirements. Physics-based numerical device simulations incorporating established HgCdTe material parameters and G-R mechanisms are used to study the performance characteristics of a long wavelength infrared (LWIR) NB nu N device with a 12 mu m cut-off wavelength. The calculated results are compared to those values obtained for an LWIR HgCdTe nBn device. Theoretical dark current density (J(dark)) values of the NB nu N device are lower by an order of magnitude or more for temperatures between 50 K and 245 K. Calculated detectivity (D*) values of 2.367 x 10(14) - 2.273 x 10(11) cm Hz(0.5)/W for temperatures ranging from 50 K and 95 K, respectively, are observed in the NB nu N structure.