Comparison of Measured Dark Current Distributions With Calculated Damage Energy Distributions in HgCdTe

Abstract

Abstract-This paper presents a combined Monte Carlo and analytic approach to the calculation of the pixel-to-pixel distribution of proton-induced damage in a HgCdTe sensor array and compares the results to measured dark current distributions after damage by 63 MeV protons. The moments of the Coulombic, nuclear elastic and nuclear inelastic damage distributions were extracted from Monte Carlo simulations and combined to form a damage distribution using the analytic techniques first described in [I]. The calculations show that the high energy recoils from the nuclear inelastic reactions (calculated using the Monte Carlo code MCNPX [2]) produce a pronounced skewing of the damage energy distribution. While the nuclear elastic component (also calculated using the MCNPX) contributes only a small fraction of the total nonionizing damage energy, its inclusion in the shape of the damage across the array is significant. The Coulombic contribution was calculated using MRED 13-51, a Geant4 [4,6] application. The comparison with the dark current distribution strongly suggests that mechanisms which are not linearly correlated with nonionizing damage produced according to collision kinematics are responsible for the observed dark current increases. This has important implications for the process of predicting the on-orbit dark current response of the HgCdTe sensor array.

Dark Current Random Telegraph Signals in Solid-State Image Sensors

“…A bump bonding is used to connect the cathode to the CMOS readout circuit [23]. Although this device is not irradiated, we choose to present its results because, to the best of our knowledge, this is the first time that DC-RTS amplitudes are reported in such a device that is today considered for space mission where the radiation environment is known to creates defects inducing dark current [23], [24] and DC-RTS in other technologies.…”