Effect of an electric field on the binding energy of impurities in semiconductor quantum wells

Abstract

The binding energy of a shallow impurity in GaAs-AlxGa1−xAs quantum wells subjected to a longitudinal electric field is calculated using a variational method with a non-separable trial wave function. The dependence of the donor binding energy U on the applied electric field F, the impurity position zi and the well width L is investigated within a larger range of well width. It is shown that for a given impurity position zi=-L/4, the field-induced variation of the binding energy for L>220 Å is quite different from that for narrower wells. The electron probability distribution in the quantum well for various impurity positions and several values of the electric field strength is also discussed. These results have very clear physical meaning.