Theoretical design and simulation of uncooled PbSe/Ge mid-wavelength infrared avalanche photodetector

To comply with SWaP 3 specifications in infrared detectors, a novel uncooled mid-wavelength infrared avalanche photodetector (MWIR-APD) architecture based on PbSe/Ge heterojunction was proposed. A maximum high gain of 40.8 was achieved, which is comparable with cooled MWIR-APDs, including HgCdTe, and type II superlattices. The theoretical simulation shows that it is the significant difference in permittivity between PbSe and Ge that results in a sufficient electric field contrast between the absorption and multiplication layers, which facilitates the structural design of this APD. Additionally, a structural parameter limit was established by investigating the variation in the punch-through and breakdown voltages. Furthermore, the decreasing PbSe thickness will improve the device’s gain but at the expense of decreasing frequency response and quantum efficiency. This PbSe/Ge APD architecture provides a new solution for the MWIR detection at room temperature.