Shallow impurity centers in semiconductor quantum well structures

Interest in the study of the behavior of shallow impurity centers in superlattices and quantum well structures is fairly recent. This paper reviews briefly both the theoretical and experimental work done in this field in the last few years. Several recent calculations of the energy levels of hydrogenic impurity states in quantum well structures, such as Ga_1?xAl_xAsGaAsGa_1?xAl_xAs, are reviewed. The behavior of these levels as a function of the quantum well size is discussed. Recent experimental data concerning the variations of the binding energies of shallow donors and acceptors as a function of the GaAs quantum well size are reviewed. A comparison between these experimental measurements and the results of recent calculations is presented.