The noise equivalent temperature difference performance of HgCdTe photodiode array

Abstract

The noise equivalent temperature difference (NETD) of Hg 1− x Cd x Te photodiode line arrays, used for the detection of radiation in the 8–12 μm spectral region is calculated. The dependence of the photodiode dark-current, signal and background photo-currents upon the photodiode cut-off wavelength and operating temperature, is presented with the material properties as parameters, and the NETD dependence on these parameters is calculated. The NETD is optimized with respect to the Hg 1− x Cd x Te molar composition, with excess carrier life-time and bulk doping level as parameters. The optimal cut-off wavelength and temperature for operating the photodiodes are derived. For current technology and focal plane temperature of 77 K, the optimal cut-off wavelength is shown to be, for an example system, in the range of 9.5–10.5 μm.