Effects Of Proton Irradiation On Performance Of The Long Wavelength Infrared InAs/GaSb Detectors

Superlattice detectors based on InAs/GaSb/AlSb material layers have demonstrated significant performance improvement in the last decade. As superlattice detectors and focal plane arrays (FPAs) became valuable candidates for space-based instruments, question of their radiation tolerance became important. In this work we investigated the effect of the proton irradiation on the performance of the long wavelength infrared InAs/GaSb photodiodes based on complementary barrier infrared detector design. We found that irradiation with 68MeV protons up to the total ionizing dose, TID=200kRad, results only a small decrease in quantum efficiency and no increase in operational bias of the photodiodes. However, the irradiation causes a significant increase in dark current. The analysis of dark current as a function of operating temperature and bias showed that the dominant contributor to the dark current in these devices changes from diffusion current to tunneling current when these detectors are irradiated. This change in the dark current mechanism can be attributed to an onset of surface leakage current, which indicates that radiation damage near the device side walls has a major contribution to the dark current increase. Moreover, thermal-cycling of the device made only a minor improvement in the device performance, indicating a proton displacement damage to the device structure.