A theoretical model for bias dependent shift of absorption spectra in quantum well infrared photodetectors

Bias dependent shift of the absorption spectrum in quantum well infrared photodetectors (QWIPs) has been reported in literature However, theoretical models for explaining this shift have either attempted to calculate the wavefunctions using cumbersome approximations or have relied on the assumption that the applied bias does not significantly affect the shape of the square well potential. In this paper, we report a new approach using Green's functions, which allows us to calculate the field-modulated density of states and the exact normalized wavefunctions for an arbitrarily shaped one-dimensional potential. We can then calculate the momentum matrix element and the absorption spectra for any given transition under the influence of an external field. It is to be noted that this approach also allows for the inclusion of inelastic scattering fields.