Charge carrier localization effects on the quantum efficiency and operating temperature range of InAs_xP_1−x/InP quantum well detectors

The effect of charge carrier localization resulting in "S-shaped" temperature dependence of the photoluminescence peak energy of InAs_xP_1−x/InP quantum wells (QWs) is distinctly revealed by the temperature dependent surface photo voltage (SPV) and photoconductivity (PC) processes. It is observed that the escape efficiency of carriers from QWs depends on the localization energy, where the carriers are unable to contribute in SPV/PC signal below a critical temperature. Below the critical temperature, carriers are strongly trapped in the localized states and are therefore unable to escape from the QW. Further, the critical temperature increases with the magnitude of localization energy of carriers. Carrier localization thus plays a pivotal role in defining the operating temperature range of InAs_xP_1−x/InP QW detectors.