THEORY OF EXCITONS BOUND TO NEUTRAL IMPURITIES IN POLAR SEMICONDUCTORS

The ground-state energy and the configuration of a complex consisting of an exciton bound to a neutral impurity are investigated. Starting from a Hamiltonian which includes the electron-phonon coupling as described by Fröhlich, we derive a mass renormalization and an effective electron-hole potential, both depending on the interparticle distances. The corresponding Schrödinger equation is solved by an ansatz which describes an exciton bound to a donor as well as to an acceptor. In addition, central-cell effects are taken into account. Numerical results for several III-V and II-VI compounds are in good agreement with experimental data. © 1979 The American Physical Society.