QWIPs DESIGNED FOR HIGH ABSORPTION AND HIGH OPERATING TEMPERATURE

Abstract

For the majority of applications involving detection of weak signals or thermal imaging, the quantum well infrared photodetector (QWIP) is designed to have the highest possible detectivity and operating temperature. The device parameters, such as the doping density, are chosen accordingly. In a different direction, the intrinsic short carrier lifetime (~ 5 ps) makes QWIPs well suited for high speed and high frequency applications. In such cases, since lasers are normally used, a high dark current can be tolerated. The most important parameter is then the absorption efficiency. For system simplicity and potential wide use, room temperature or near room temperature (reachable by thermo-electric cooling) operations are desirable. This paper discusses the QWIP design for high absorption and elevated temperature operation, and present a systematic experimental study on a set of GaAs/AlGaAs QWIPs with different doping densities. High absorption (~ 100%) and up to room temperature operation are achieved in devices having high doping densities and 100 quantum wells.