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The inhuence of an applied electric field on shallow donor and acceptor states in GaAs-(Ga, Al)As quantum wells is studied. We work within the effective-mass approximation and adopt a trial envelope wave function for the impurity carrier, which leads to the exact results for vanishing applied electric fields and limiting values of the quantum-well thickness. Results for the binding energies and density of impurity states as functions of the impurity position, well thicknesses, and applied electric field are reported. Some results for the effects of electric field on the donor-related optical properties are also presented. As a general feature, the density of impurity states and impurityrelated optical absorption for finite electric fields exhibit three van Hovelike 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.

A theoretical study of the photoluminescence spectrum associated with shallow acceptors in GaAs-(Ga, A1)As quantum wells is performed. As a general feature, there are two special structures in the acceptor-related spectrum: an edge associated with transitions involving acceptors at the center of the well, and a peak associated with transitions related to on-edge acceptors. The photoluminescence line shape depends on the temperature, the quasi-Fermi energy of the conductionsubband electron gas, and on the acceptor distribution along the quantum well. It is suggested that an analysis of the acceptor-photoluminescence line shape could allow an experimental determination of the quasi-Fermi-energy level of the conduction-subband electron gas as well as of the onedge-acceptor binding energy. Experimental results of unintentionally doped multiple-quantumwell GaAs-Gao, Alo, As samples by Miller et al. [Phys. Rev. B 25, 3871 (1982)] and of single quantum wells of GaAs-Gao gsAlp, gAs by Meynadier et al. [J. Appl. Phys. 58, 4307 (1985)] are in excellent agreement with theoretical results obtained with a homogeneous distribution of acceptor impurities along the GaAs layer and a convenient choice of the quasi-Fermi-energy level.