Hg/sub 1-x/Cd/sub x/Te metal-semiconductor-metal (MSM) photodetectors

Metal-semiconductor-metal (MSM) detectors with active layers of Hg/sub 1-x/Cd/sub x/Te (x=0.62-0.74) and electrode spacings of 2, 4, and 6 mu m have been fabricated and characterized. Direct-current measurements have shown a low dark current and high responsivity from 0.15 to 1.5 A/W at 10-V bias. The lowest values of dark current (0.16 mA cm/sup 2/) were obtained for detectors which incorporated an overlayer of CdTe. For detectors without the overlayer, increasing the Cd mole fraction resulted in a decrease in the dark current and a reduction in the 300-nm responsivity. Measurements of frequency response for these detectors show a maximum loss of 8 dB to 20 GHz. These results compare favorably with high-performance MSM detectors based on In/sub 0.53/Ga/sub 0.47/As with a lattice-matched barrier layer of In/sub 0.52/Al/sub 0.48/As.<
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