<title>Optical absorption associated to shallow impurity states in GaAs(Ga,Al)As quantum wells: electric-field effects</title>

Abstract

The optical-absorption spectra associated with transitions between the n equals 1 valence subband and the donor-impurity band and between the acceptor-impurity band and the n equals 1 conduction subband have been calculated for GaAs-(Ga,Al)As quantum-wells under constant applied electric field perpendicular to the interfaces. We have described the impurity states within a variational scheme in the effective-mass approximation. The distribution of impurities in the quantum well has been assumed to be homogeneous and interaction between impurities neglected. As a general feature, the impurity-related optical absorption for finite electric fields exhibits three van Hove-like singularities corresponding to the binding energies associated with impurities at the two edges of the quantum well and at the position at which the binding energy has a maximum.