Experimental Evaluation of the Proton Non-ionizing Energy Loss in II-VI and III-V Superlattice Infrared Materials

Abstract Infrared materials used in space-based infrared sensing systems are susceptible to displacement damage from protons in the space radiation environment, leading to a progressive degradation of the system’s sensitivity over its mission life. When protons traverse a material, they interact via both ionizing energy loss or linear energy transfer, generating excess electron–hole pairs, and non-ionizing energy loss (NIEL), generating interstitial/vacancy pairs. These additional defects often act as carrier recombination centers, which reduce a sensor’s sensitivity. Here, the 130 K minority carrier lifetime is measured for a mid-wave infrared InAs/InAsSb superlattice and HgCdTe as a function of proton fluence to evaluate the lifetime degradation as a function of proton energy from 2 MeV to 52 MeV, to provide a measure of the relative proton-energy-dependent defect introduction rate in each of these materials. The results indicate that the product of the defect survival fraction and the defect impact on recombination ( $$\xi \sigma \nu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ξ</mml:mi> <mml:mi>σ</mml:mi> <mml:mi>ν</mml:mi> </mml:mrow> </mml:math> ) is 130 $$\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> higher for the InAs/InAsSb superlattice than for HgCdTe. Furthermore, the damage generally scales with NIEL as a function of proton energy; however, higher energy deviations from the scaling suggest either a proton energy dependence to the impact defect survival fraction product or inaccuracies in the theoretical NIEL trend for these materials. Example calculations of the on-orbit lifetime difference indicate that the deviations have a negligible impact due to the relatively low protons flux at higher energies.