Variation of generation-recombination noise density with 300 K background flux in epitaxial LWIR Hg 1-x Cd x Te photoconductors having three-layer light absorbing configuration

Abstract

Spectral density of "generation-recombination" noise voltage <δV 2 gr > ("g-r noise") in photoconductive Hg 1-x Cd x Te infrared radiation detectors with absorber n-Hg 1-x Cd x Te layer was calculated. Variations of <δV 2 gr > with doping level (n ≈ N d ), ambient background flux density (Q bgr , T bgr ≈ 300 K), electrical bias (V b /I b ) and pixel active area were analyzed. Spectral density of low-frequency noise as superposition of Flicker-noise "1/f", g-r noise resulting from fluctuations in generation-recombination rates of equilibrium (thermal) charge carriers <δV 2 gr,th > and excess charge carriers exited by background photons <δV 2 gr,bgr > and Johnson-Nyquist noise <δV 2 JN > were examined in small active area (30 µm × 30 µm and 50 µm × 50 µm) Hg 1-x Cd x Te photoconductors based on MBE-grown multi-layer structures. Noise measurements were performed on Long-Wave (LWIR) PC MCT detectors with responsivity peak wavelength 10 ≤ λ p ≤ 12 µ m at operating temperature T op ≈ 78 K. Tested PC MCT detectors show extremely low spectral density of excess. Measured dependencies of g-r noise voltage spectral density have confirmed BLIP mode of photoconductors up to FOV=10 0 where D*(λ p ) exceed 2×10 11 Jones.