Excited states of shallow acceptors in ZnSe

Excitation spectra of different donor-acceptor pair emission bands and selective pair luminescence spectra were measured on cubic ZnSe crystals with different impurity contents. For the Na and Li acceptor we found the excited states with $s$ symmetry up to $4S$, as well as the four $2P$ excited states. These experiments further demonstrate that the acceptor involved in the $R$ pair band reported in the literature is substitutional Li. The observed excited acceptor states are compared to results of the effective-mass theory of Baldereschi and Lipari, after the theoretical state energies have been scaled by the experimentally determined Rydberg energy of the respective acceptor.