Self-compensation of the phosphorus acceptor in ZnSe

ZnSe epilayers doped with plasma-activated phosphorus have been investigated by means of optical and electrical measurements. It is found that P_Se forms a shallow acceptor with binding energy of 85 meV which is identified in the optical emission spectra. In these samples we also observe an energy level near 90 meV from the valence band using deep level transient spectroscopy. We assign it to the P_Se acceptor identified in photoluminescence. Also, deeper levels were observed with binding energies up to 450 meV. Some of them are metastable and give rise to persistent photoconductivity. We discuss their relevance taking into account that all samples investigated in the study were highly resistive.