Lead Selenide Detectors for Intermediate Temperature Operation

Abstract

At about 195°K, PbSe detectors have a much higher detectivity in the 3.5-μ to 5.2-μ wavelength region than any other type of infrared detector. Detectors with a D* (4.4 μ, 2500 cps) greater than 3 × 1010 cm (cps)½/W are standard. These detectors are partially background limited at 195°K and can be improved to at least 6 × 1010 cm (cps)½/W by appropriate radiation shielding. When used at room temperature (295°K), these films exhibit peak detectivity at about 3.8 μ and about one-half detectivity at 4.4 μ. Although the absolute magnitude of the peak detectivity at 295°K is considerably less than that at 195°K, it is better than a thermal detector, such as a bolometer or thermocouple. In addition, the time constant at 295°K is less than 2 μsec.