Density of states and optical-absorption spectra of shallow impurities in quantum wells under the influence of a longitudinal electric field

We have calculated the densities of states and the optical-absorption spectra of shallow donors and acceptors in GaAs-(Ga,Al)As quantum wells under the influence of a constant electric field applied parallel to the growth axis. The impurity binding energies were calculated as functions of the impurity position in a quantum well of infinite depth, where we have used a variational procedure within the effective-mass approximation. The main feature found was a quenching of one of the peaks due to interface impurities at moderate electric fields. We compare these optical-absorption spectra with previous calculations in the absence of an electric field.