The Influence of Correlation and Band Structure Effects on an Exciton Weakly Bound to an Isoelectronic Impurity

Abstract

AbstractA variational method for the ground state of an exciton bound to an isoelectronic impurity is developed. In contrast to the HTL model the correlation between the electron and the hole is taken into account for the first time, using instead of the hole coordinates the relative electron‐hole coordinates. In this way it is possible to describe the whole region from strong exciton binding, where the HTL model is a good approximation, to the free‐exciton limit, impossible to reach in the HTL model. Furthermore, the method predicts a small potential region (≈ 10 meV) above the threshold for electron binding, where the exciton is still bound. Because the impurity potential is short‐ranged instead of the effective‐mass‐approximation a band structure parametrization of the lowest conduction band is used. As a numerical example the case of GaP:N is considered.