Model for phonon-assisted indirect recombination at impurity sites in semiconductors: A test of impurity wave-function theories

A new method for studying the wave functions associated with defect levels is presented. The method is based on a model that includes the role of intrinsic lattice phonons in indirect electron-hole recombination at impurity sites in semiconductors; the model contains information about the impurity-phonon matrix elements and the intrinsic phonon dispersion relations as well. In particular, it can be used in conjunction with experimental data as a test of the accuracy of impurity wave-function models. As an illustration, an application to the acoustic-phonon sidebands in the low-temperature luminescence spectrum of the N-bound excition in GaP is described wherein the method is used to test the Koster-Slater one-band one-site approximation for the electron wave function.