Photovoltaic HgCdTe detectors for advanced GOES instruments

There has been significant progress made during the past several years in PV HgCdTe technology for advanced long wavelength remote sensing applications. Useful cutoffs wavelength shave been extended to beyond 17.0 micrometers . Junction quality has been improved to the point that D* > 3 X 1011 cm-(root) Hz/W can be achieved 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 long linear multiplexed arrays of PV HgCdTe detectors with cutoff wavelengths extending as far as 15.0 micrometers at 60 K. PV HgCdTe offers many advantages over PC HgCdTe for multiplexers are possible, backside-illuminated 2D 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, we review recent data for linear arrays of PV HgCdTe with cutoff wavelengths as long as 17.5 micrometers at 70 K, and we project that PV HgCdTe should be able to meet or exceed the present demanding GOES LW Sounder D* requirements at T equals 100 K, with the additional benefits of negligible 1/f noise and better linearity.