Investigating Dark Current Random Telegraph Signal in an HgCdTe H4RG-10 Infrared Detector for Space Application

Dark Current Random Telegraph Signal (DC-RTS) characteristics of astronomical H4RG-10 HgCdTe Near Infrared (NIR) image sensors are investigated before irradiation, for cumulative radiation dose up to 5 krad(Si), and for subsequent thermal annealing. This study is carried out as part of the qualification testing for the Roman Space Telescope Wide Field Instrument sensor chip assembly. Two proton energies, 64 and 9 MeV, are explored using one detector per energy. Pre-rad results show a RTS part-to-part variability that is highly correlated with initial dark current variability. Pre-rad and post-rad RTS pixels share the same physical characteristics, suggesting a common physical origin. RTS pixel occurrence and location are also found to be very sensitive to room temperature annealing. Results show that the RTS pixel population after irradiation approximates 0.037% of the pixels in the worst case, thus resulting in a very limited impact on the sensor's performance degradation up to the proton fluences in this study.