ELECTRONIC STATES ASSOCIATED WITH THE SUBSTITUTIONAL NITROGEN IMPURITY IN GAPXAS1-X

The authors have studied the process of formation of bound states associated with the substitutional nitrogen impurity in GaPxAs 1-x as a function of the change in band structure with alloy composition. The host crystal band structure and the impurity potential are represented by local pseudopotentials, using the virtual crystal approximation. The problems of finding a self-consistent potential are dealt with in some detail and it is demonstrated that the results obtained by perturbation theory (screening) may differ from those obtained by large-scale computer calculations typically by 10-15%. The magnitude of this correction is affected by processes similar to those participating in the formation of deep localised states.