Device physics and modeling of multiple quantum well infrared photodetectors

In this paper we present the physical effects in quantum well infrared photodetectors (QWIPs) utilizing intersubband electron transitions. We show, using numerical modeling, that the operation of QWIP is associated with the nonuniform distribution of the electric field and other physical quantities due to the recharging of the QWs near the emitter contact. The high electric field in the emitter barrier which provides tunneling electron injection is controlled by applied voltage and infrared radiation. The transient photoelectric effects in QWIPs are determined by three time constants-electron capture time to the QWs, transit time through the QWIP structure, and recharging time of the QWs. The transient photocurrent in QWIPs with high photocurrent gain is composed of two components. The fast transient is limited by the carrier transit time, and the slow transient, exhibiting the multiplication of photocurrent, is governed by the QW recharging time. This study shows that contact and distributed effects play an important role in determining both the steady-state and transient QWIP characteristics.