1 November 1993 Development of LPE-grown HgCdTe 64 x 64 FPA with a cutoff wavelength of 10.6 μm
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Abstract
We have developed a hybrid HgCdTe focal plane array (FPA) for wavelengths from 8 to 11 micrometers . We describe how we fabricated our back illuminated 64 X 64-element photodiode array on a liquid phase epitaxial (LPE) HgCdTe wafer, and a Si CCD multiplexer with line address readout. We optimized carrier concentration in the p-type HgCdTe layer to maximize charge injection efficiency to the Si CCD readout circuit to more than 99.3%. We achieved excellent uniformity of characteristics of the photodiode array, which is very important for an IRFPA, by using LPE HgCdTe grown with a tipping method, and passivating the photodiode array with an anodic sulfide of HgCdTe. We obtained an average product of zero-bias resistance and area (RoA) of 9.1 (Omega) cm2 with a cutoff wavelength of 10.6 micrometers at 77 K. We used line address readout to give a large charge storage capacity of 4 X 107 electrons. We estimated a noise equivalent temperature difference (NETD) of 0.08 K with F/2.5 optics, including fixed pattern noise. We tried some preliminary experiments to reduce the crosstalk from photogenerated carriers which spread laterally into the epitaxial layer. We improved the modulation transfer function (MTF) at Nyquist spatial frequency from the conventional 35% to 60% by using a crosswise drain structure around each photosensitive n+ on p diode.
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Toshio Kanno, Toshio Kanno, Minoru Saga, Minoru Saga, Nobuyuki Kajihara, Nobuyuki Kajihara, Kenji Awamoto, Kenji Awamoto, Gen Sudo, Gen Sudo, Yuichiro Ito, Yuichiro Ito, Hiroyuki Ishizaki, Hiroyuki Ishizaki, } "Development of LPE-grown HgCdTe 64 x 64 FPA with a cutoff wavelength of 10.6 μm", Proc. SPIE 2020, Infrared Technology XIX, (1 November 1993); doi: 10.1117/12.160580; https://doi.org/10.1117/12.160580
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