New Pair Spectra in Gallium Phosphide

Crystals of GaP doped with Zn+Te, Zn+Se, Cd+Te, and Cd+Se were grown from gallium-rich solutions contained in pyrolytic boron nitride crucibles, using vapor-grown GaP as source material. The low-temperature photoluminescence of these crystals reveals the presence of new pair spectra involving zinc or cadmium on gallium sites and tellurium or selenium on phosphorus sites (type II spectra). The values of ($E_A+E_D$), the sum of the acceptor and donor binding energies, derived from the spectra are in excellent agreement with the values predicted from previously observed pair spectra. The data on all the previously observed spectra have also been recalculated to yield more consistent values of ($E_A+E_D$) and the Van der Waals parameter.