Characterization of high performances of long wave and very long wave HgCdTe staring arrays

Abstract

Based on the mature and reproducible HgCdTe process developed by CEA-LETI-Infrared Laboratory and industrialized by Sofradir, two new detectors with a cut-off wavelength tuned between 9 μm and 12 μm have been developed. For compact LW cameras, Sofradir produces a high resolution 25 μm pitch 384×288 infrared focal plane array (IRFPA) with a cut-off wavelength between 9 μm and 10 μm, and an operational temperature between 77 and 85 Kelvin. The manufacturing of this detector relies on the standard HgCdTe production process with the latest uniformity improvements. For VLW applications such as spectroscopy or broadband low flux applications, an improved HgCdTe material with optimized Liquid Phase Epitaxy (LPE) and Photovoltaic (PV) detector process has been developed by LIR and Sofradir to get very low dark currents. These 30 μm pitch 320x256 detector arrays have cut-off wavelengths above 12 μm below 50 K and their dark current is compatible with very low flux applications. The performances of these new LW and VLW IR detectors are presented in this paper as well as the development trends for LW detectors at LETI and Sofradir.