Developments in MOVPE HgCdTe arrays for passive and active infrared imaging

Abstract

SELEX Galileo Infrared Ltd has developed a range of 3rd Generation infrared detectors based on HgCdTe grown by Metal Organic Vapour Phase Epitaxy (MOVPE) on low cost GaAs substrates. There have been four key development aims reducing the cost especially for large arrays, extending the wavelength range, improving the operating temperature for lower power, size and weight cameras and increasing the functionality. Despite a 14% lattice mismatch between GaAs and HgCdTe MOVPE arrays show few symptoms of misfit dislocations even in longwave detectors. The key factors in the growth and device technology are described in this paper to explain at a scientific level the radiometric quality of MOVPE arrays. A feature of the past few years has been the increasingly sophisticated products that are emerging thanks to custom designed silicon readout devices. Three devices are described as examples: a multifunctional device that can operate as an active or passive imager with built-in range finder, a 3-side buttable megapixel array and an ultra-low noise device designed for scientific applications.