Comparison of Pre-and Post-Irradiation Low-Frequency Noise Spectra of Midwave Infrared nBn Detectors With Superlattice Absorbers

Noise spectra of type-II strained layer superlattice midwave infrared photodetectors were compared pre-and postirradiation by a proton fluence of 7.5 x 10(11) cm(-2) [total ionizing dose equivalent of 100 krad (Si)] and related to the shot noise limit at biases ranging from +200 to -800 mV and temperatures of 130 and 160 K. Pre-irradiation dark current at 130 K was 7.5X Rule '07 and increased to 59X Rule '07 after irradiation. The pre-irradiation noise spectra were within one order of magnitude of the shot noise prediction, while post-irradiation noise spectra were close to two orders higher, indicating the introduction of nonshot-like noise sources.