New device models of quantum well infrared photodetectors

Summary form only given. Recent numerical work (Ershov et al, 1997; Thibaudeau et al, 1996) has shown that at low operating temperatures or large incident photon fluxes, carriers deplete from the quantum wells near the emitter contact in a quantum well infrared photodetector (QWIP). This work finds a physical model (with closed form analytical expressions) which explains the recent numerical work on carrier depletion in QWIPs. The physical model found in this work is computationally much less intensive than the full numerical model, but retains the essential physics. As an example, we have considered device designs with the same periodic structure (the same compositions and layer widths) throughout the QWIP. In our physical model, the incident radiative flux was fixed, while the device behavior was studied for a varying applied bias. The current was seen to rise linearly with the applied bias in the different operating regimes, but with a different differential resistance in each operating regime. The physics behind this device characteristic was studied, and results are summarized here.