Determination of acceptor binding energies in ZnSe.

Luminescence and photoconductivity measurements were performed on MBE-grown ZnSe layers with various arsenic concentrations. Two shallow acceptor levels with binding energies of 125 and 260 meV were found. The acceptor binding energies were determined from the photoluminescence of bound excitons using Haynes' rule, by the evaluation of donor - acceptor pair emission and from the onset of the photoconductivity signal. Increasing the As content in order to increase the number of shallow acceptors resulted in highly compensated samples. In ZnSe epilayers, which are under tensile strain due to the different thermal expansion coefficients, Haynes' rule can be applied by evaluating the energetic difference between the heavy hole branch of the free exciton and the acceptor bound exciton.