Temperature dependence of quantum efficiency in Quantum Dot Infrared Photodetectors

The behavior of quantum efficiency in QDIPs was studied in details with simple InAs/GaAs QDs and DWELL QDs structures. Despite of the large difference of the excited state energy between the two samples, the QE shows similar trends with temperature and bias voltage. The voltage to reach the QE plateau decreases with temperature and the maximum QE decreases with temperature. Considering the repulsive potential from the charge inside the QDs, the effective barrier height and thickness for the photoexcited carrier is much reduced and the QE variation with voltage follows the calculated tunneling probability. Furthermore, the multi-phonon interaction which leads to the relaxation of the excited carrier is shown to be important to the decrease of QE with temperature. The enhanced relaxation rate decreases the maximum QE value at higher temperature.