Evaluating the GeoSnap 13-μm cutoff HgCdTe detector for mid-IR ground-based astronomy

Abstract

New mid-infrared HgCdTe (MCT) detector arrays developed in collaboration with Teledyne Imaging Sensors (TIS) have paved the way for improved 10- (Formula presented.) m sensors for space- and ground-based observatories. Building on the successful development of longwave HAWAII-2RGs for space missions such as NEO Surveyor, we characterize the first 13- (Formula presented.) m GeoSnap detector manufactured to overcome the challenges of high-background rates inherent in ground-based mid-IR astronomy. This test device merges the longwave HgCdTe photosensitive material with Teledyne's (Formula presented.) GeoSnap-18 (18- (Formula presented.) m pixel) focal plane module, which is equipped with a capacitive transimpedance amplifier (CTIA) readout circuit paired with an onboard 14-bit analog-to-digital converter (ADC). The final assembly yields a mid-IR detector with high QE, fast readout (>85 Hz), large well depth (>1.2 million electrons), and linear readout. Longwave GeoSnap arrays would ideally be deployed on existing ground-based telescopes as well as the next generation of extremely large telescopes. While employing advanced adaptive optics (AO) along with state-of-the-art diffraction suppression techniques, instruments utilizing these detectors could attain background- and diffraction-limited imaging at inner working angles <10 (Formula presented.) /D, providing improved contrast-limited performance compared with JWST MIRI while operating at comparable wavelengths. We describe the performance characteristics of the 13- (Formula presented.) m GeoSnap array operating between 38 (Formula presented.) 45 K, including quantum efficiency, well depth, linearity, gain, dark current, and frequency-dependent ((Formula presented.)) noise profile. © 2023 The Authors. Astronomische Nachrichten published by Wiley-VCH GmbH.