Figures of merit estimation of quantum well infrared photodetectors using interband and intersubbanad transitions

Abstract

Recent commercial and military applications have demanded photodetectors with high sensitivity, high selectivity and multispectral capability for detection and identification of objects. These characteristics have been found in quantum well infrared photodetectors (QWIP). Driven by those applications and aiming to improve the analysis and the design of QWiPs, a technique was developed for numerically estimate their main figures of merit such as IxV characteristics, dark current, quantum efficiency, responsivity, etc. The mathematical models of QWIP figures of merit, extracted from the references [1-4], can be adapted according to the semiconductor structure configuration. The main issue in this work was to be able to estimate the QWIPs' quantized energy levels inside the wells, their in respective wavefunctions and the transition rates between them. Two kinds of transitions were of special interest: Interband and intersubband transitions. in both cases, depending on the QWIP's the structure characteristics and the external bias, transitions can occur from a confined state to a was continuum one. Interband transitions in non-doped wells and intersubband transitions in n-doped figures wells were studied and modeled using a computational tool developed to solve self-consistently the current, Schrodinger-Poisson equation with the help of the shooting method [5]. The shooting method was used due to its ability to handle multilayer structures with any potential profile, making the design this present more flexible. This approach allowed computing the stark effect caused by the external electric field, used and predict quite accurately the figures of merit of devices under bias. A good agreement between our cited theoretical predictions and the measurements made in several structures [1], [4] shows that this technique is suitable for analysis and design of practical devices.