Infrared Nanocrystals for Space Application: Hardness to Irradiations

ABSTRACT Colloidal nanomaterials are now a cost‐effective strategy for the design of infrared imagers. Their increased maturity brings them to the point where the evaluation of their potential for space and astronomy applications becomes relevant. The first step is to test their robustness against irradiation, since this process is responsible for the performance degradation of most imagers. In this study, we explore the potential of HgTe nanocrystals for short‐wave infrared sensing under X‐ray and He + ion irradiation. To first assess the degradation of the material itself, we test the evolution of a single‐pixel photoconductive device upon irradiation and observe that only marginal degradation occurs for doses relevant to space applications, and degradation only occurs at a very high threshold, making this colloidal semiconductor quite promising to operate in harsh radiation environments. Complementary spectroscopic studies reveal very different degradation mechanisms upon X‐ray (leading to oxidation) and He + ion (sintering particles). We tested the potential of this material in a focal plane array and observed degradation, though not preventing imaging, in a range of doses where no effect was observed for the simple photoconductive device. This suggests that the CMOS readout circuit might be the bottleneck regarding operation under radiation.