<title>Advances in 15-um HgCdTe photovoltaic and photoconductive detector technology for remote sensing</title>

Abstract

There has been significant progress during the past several years in photovoltaic (PV) HgCdTe technology for advanced long wavelength remote sensing applications. Useful cutoff wavelengths have been extended to beyond 17.0 micrometer. Junction quality has been improved to the point that D* greater than 3 multiplied by 1011 cm-(root)Hz/W can be achieved in arrays at temperatures of 60 - 65 K. The atmospheric infrared sounder (AIRS) instrument, scheduled for launch in the year 2000 as part of the NASA EOS Program, uses over 4000 PV HgCdTe detector elements organized into ten linear multiplexed arrays, with cutoff wavelengths extending as far as 15.0 micrometer at 60 K. The AIRS instrument also uses two long linear arrays of photoconductive (PC) HgCdTe detectors for the 13.7 - 15.4 micrometer band. These PC detector arrays have cutoff wavelengths of 16.0 - 17.0 micrometer and achieve D* values of 3 - 5 multiplied by 1011 cm-(root)Hz/W at 60 K. PV HgCdTe offers many advantages over PC HgCdTe for advanced remote sensing instruments: negligible 1/f noise, much higher impedance so that cold preamps or multiplexers are possible, configurational versatility with backside- illuminated two-dimensional arrays of closely spaced elements, 10X - 100X better linearity, dc coupling for measuring the total incident photon flux, and a (root)2 higher BLIP D* limit. In this paper we compare the relative merits of PV and PC HgCdTe for advanced remote sensing instruments, and we review recent data for both PV and PC HgCdTe arrays with cutoff wavelengths as long as 17.5 micrometer.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.