TWO COLOR Hg1-xCdxTe PHOTOCONDUCTIVE IR DETECTORS SENSITIVE TO RADIATION FROM 3-5 μm and 8-14 μm BANDS

Two color Hg_1-xCd_x Te Photoconductive IR detectors which are concentrical sandwich have been fabricated by rising n-type bulk crystals in our laboratory. The composition values of Hg_1-xCd_xTe are x≈0.3 and x≈0.2, respectively, and hence, the two color detectors are sensitive to radiation from 3-5μm and 8-14μm bands. As an example, operating at 77 K with a 300 K, 180° FOV background, peak detectivities D‘(λ_p,980,1) as high as 5.9 x 10¹⁰ cmHz^½/W and 2.3 x 10¹⁰cmHz^1/2/W have been achieved for top and bottom elements, respectively, the top element has peak wevelength λ_p of 5.2μm and cut-ofT wavelength λ_c of 5.6 μm, whereas the bottom one ha λ_ps of 12.μ and λ_c 13.2μm. Excepting mentioned above, we also discuss some problems relative to the fabrication and performance of the two color Hg_1-xCd_xTe photoconductive IR detectors.