Recent advances in the development of infrared multispectral 1282FPAs

Abstract

In this paper we present a status of the activity of the LETI infrared laboratory in the field of HgCdTe infrared multispectral detectors. The multilayer doped structures needed to achieve two color pixels are grown by molecular beam epitaxy (MBE) (211)HgCdTe on lattice matched CdZnTe substrates. The device structure is n+ppn and is spatially coherent. The long wavelength layer is a planar like n+/p diode and is made by ion implantation while the shorter wavelength p-n diode is made in-situ during the MBE growth using Indium impurity doping. The last junction is isolated by mesa etch. The detectors are interconnected by indium bumps to a CMOS readout circuit. One or two indium bumps per pixel are used to address sequentially or simultaneously the two wavelengths, the detector pitch being 50micrometers or 60micrometers respectively. Elementary detectors exhibit performances in each band which are very close to those obtained in single color detectors with our standard technology. The Si-CMOS read-out circuits are specially designed to optimize the best performance of the IRCMOS focal plane arrays (FPA) in both wavelengths. The electro-optical performances of a two color IRCMOS FPA with a complexity of 128x128 pixels (pitch of 50micrometers ) operating sequentially within the (3-5micrometers ) middle wavelength infrared range (MWIR) at 77K will be presented.