Effects of thermally generated carrier and temperature dependence mobility in InSb photoconductive detector under CW 10.6 µm laser irradiation

The response mechanism of n-type indium antimonide photoconductive detectors under intense continuous wave (CW) 10.6 µm laser irradiation is investigated. The magnitude of the Voc signals and the exact shape of the signals vary greatly with laser power density and irradiation time. It is found that the signals begin to decrease at a critical time when laser power density is held in a constant value. If the irradiation time is fixed, the signals begin to decrease in a critical laser power density. The Voc signals for both radiation process and the end of laser irradiation have two different response time scales. A two-dimensional model of the detector for CW laser irradiation is presented. The calculated response curves agree well with the experimental results. The two separate time scales are found to be due to two thermally resistive bonding layers. Temperature-dependent mobility is the domain mechanism for the increasing tendency of Voc signals, and the decreasing tendency results from thermally generated carrier effect. (paper)