Feasibility of Gallium Nitride for Astronomical Charge-Coupled Devices

Abstract

All astronomical missions use charge-coupled devices (CCDs) as vital organs. Usually, silicon (Si) is preferred to build them, which does not perform well without enhancements such as anti-reflection (AR) coatings. Such devices exhibit poor performance in the large (> 800 nm) and small (< 500 nm) wavelength ranges, even with AR coatings. We present studies that signify gallium nitride (GaN) as a potential replacement for Si in astronomical CCDs that operate in a wide wavelength range. For this purpose, SILVACO TCAD software has been used for simulating and comparing the electronic and optical properties of a GaN CCD pixel with a Gaia astrometric field (AF) CCD pixel. Our observations demonstrate that the electronic and optical performance of the GaN-based CCD pixel is significantly better than the Si-based AF CCD pixel. These findings can prove to be the bedrock of future astronomical exploration and broadband astronomical CCDs, as the simulated GaN CCD pixel exhibits a high quantum efficiency even without any reinforcements.