Proton Radiation Effects on Low-Flux P-on-N Short-Wavelength Infrared HgCdTe Focal Plane Array

This article investigates the effects of proton radiation on low-flux P-on-N short-wavelength infrared (SWIR) mercury-cadmium-telluride (HgCdTe or MCT) focal plane arrays (FPAs). The study is motivated by the need to investigate and characterize the degradation induced by proton irradiation on such devices. Three steps of irradiation were conducted using 63-MeV protons with a cumulative fluence up to $4.7 \times 10^{11}$ protons/cm2. Dark-signal degradation was observed after irradiation. The degradation evolved linearly up to the final fluence, with the highest dark signal reaching 2.6 e−/s, and annealed completely after a thermal cycle at room temperature. A pixel-to-pixel count of incident protons during an irradiation step also revealed a linear degradation of the dark signal over a large statistic of more than 100 k pixels. A degradation index was estimated using the fluence obtained with the facility dosimeter and the incident proton count method developed in this study. The values obtained are similar using both methods, giving a robust method of calculation of the degradation index following 63-MeV proton irradiations in our sensor technology.