Numerical simulation of the effects of InAlSb barrier layers on the InSb mid-infrared photodetectors on a mismatched substrate

摘要

Epitaxial growth of a high-quality InSb layer on a mismatched substrate which provides a path to monolithicallyintegrate InSb-based photonic devices and Si/GaAs-based electronic devices on a single wafer. This work is an attemptto investigate the effects of In_(0.9)Al_(0.1)Sb electron barrier layers on the electrical and optical properties of the InSbphotodetectors on a mismatched substrate. The structure of InSb photodetector is p-i-n type where i-layer is theunintentionally n-type doped. A 25 nm In_(0.9)Al_(0.1)Sb layer locates in the i-layer. At 77 K, InAlSb barrier can effectivelydecrease dark current due to it completely suppresses the generation and recombination current and tunneling current andpartially suppresses the diffusion current. The different dark current mechanisms (diffusion, generation andrecombination, tunneling) are discussed associated with the bandgap diagrams. For the simulation of photoresponse, theincident light is set to be 5.3 μm. At 77 K, the existence of InAlSb layer doesn’t influence the absorption of incident lightdue to its limited thickness, however, the InAlSb layer separates the i-layer and impedes the transportation of electrons.Therefore, the InAlSb layer decrease the photoresponse of InSb detector and its effects is more remarkable when thediffusion length of hole is around 5 μm or its location is near the surface of the detector. According to the simulation,optimizing the location of the In_(0.9)Al_(0.1)Sb is important to increase the performance of InSb photodetectors on amismatched substrate.