Local Field Corrections to the Binding Energies of Core Excitons and Shallow Impurities in Semiconductors

摘要

The authors have used perturbation theory to study the corrections to the ground state binding energy of a shallow hydrogenic core exciton or impurity state, due to the non-locality and directionality of the screened Coulomb potential. The cubic screened potential is constructed by means of a model dielectric matrix, adjusted on exact RPA calculations at q = O. The effect of the new off-diagonal part is in this shallow limit to cause a very small decrease of binding energies in first order. The second-order effects are negligible. Numerical estimates for a hypothetical single-valley spherical Si and for GaAs are discussed. It is concluded that if large binding energies of core excitons do indeed exist, they must have a different explanation. (Atomindex citation 13:660334)