Investigating reciprocity failure in 1.7-micron cut-off HgCdTe detectors

TL;DR

This study investigates flux-dependent non-linearity in 1.7-micron HgCdTe detectors, measuring reciprocity failure across a wide dynamic range and observing significant variability among detectors with no wavelength dependence.

Contribution

The paper presents a dedicated test station and detailed measurements revealing the range and spatial variation of reciprocity failure in HgCdTe detectors, a phenomenon not well understood before.

Findings

Reciprocity failure varies from <0.5%/decade to ~10%/decade among detectors.

No wavelength dependence of reciprocity failure was observed.

Spatial variation in reciprocity failure exists within individual detectors.

Abstract

Flux dependent non-linearity (reciprocity failure) in HgCdTe NIR detectors with 1.7 micron cut-off was investigated. A dedicated test station was designed and built to measure reciprocity failure over the full dynamic range of near infrared detectors. For flux levels between 1 and 100,000 photons/sec a limiting sensitivity to reciprocity failure of 0.3%/decade was achieved. First measurements on several engineering grade 1.7 micron cut-off HgCdTe detectors show a wide range of reciprocity failure, from less than 0.5%/decade to about 10%/decade. For at least two of the tested detectors, significant spatial variation in the effect was observed. No indication for wavelength dependency was found. The origin of reciprocity failure is currently not well understood. In this paper we present details of our experimental set-up and show the results of measurements for several detectors.