Impurity Interaction on Excited Acceptor States in GaP

Abstract

The lowest excited donor–acceptor pair states in GaP are monitored as a function of the pair separation R by luminescence excitation spectroscopy. They are interpreted in terms of the excited acceptor states 2P_3/2, 2P_5/2(Γ₇) perturbed by the Coulomb field of the donor. The impurity interaction causes an increase ΔE(R) of the corresponding binding energies in the relevant range of R < 30 Å following the empirical law ΔE ∝ exp (−R/R₀). The theoretical interpretation of the impurity interaction is based on the Coulomb overlap between the donor ground and acceptor excited states. Within a perturbational scheme hydrogen‐like wave functions are used with modified effective Bohr radii included. The first‐order calculations reflect the main features of the experimental results.