Advanced infrared detectors for future missile seekers

Abstract

New technology was utilized to design and fabricate a self-filtering infrared detector (SFD) optimized for a specific target signature. The SFD was prepared from vacuum deposited, composition-tuned epitaxial films of the semiconductor alloy, PbS(x)Se(1-x). A filter and detector layer were both grown on opposite sides of a BaF(2) substrate. The detector element was a p-n junction formed by depositing a Pb contact onto a p-type detector layer surrounded by a Au ohmic contact. The optical cuton and cutoff wavelengths were composition-tuned to 4.0 and 5.0 um by adjusting x in both layers. The measured spectral response of the SFD device was in good agreement with theoretical calculations, whereas, the quantum efficiency was below. The device resistance was two orders of magnitude below the predicted values due to surface leakage. This leakage also caused the responsitivity and detectivity to be lower that the predicted values. Application of this technology shows great promise provided these problems can be resolved.