Photoluminescence and X-Ray Photoelectron Spectroscopy of p-Type Phosphorus-Doped ZnO Films Prepared by MOCVD

Reproducible p-type phosphorus-doped ZnO (p-ZnO:P) films are prepared on semi-insulating InP substrates by metal-organic chemical vapour deposition technology. The electrical properties of these films show a hole concentration of 9.02×1017cm^-3, a mobility of 1.05cm²/V s, and a resistivity of 6.6 Ω・cm. Obvious acceptor-bound-exciton-related emission and P-induced zinc vacancy (V_Zn) emission are observed by low-temperature photoluminescence spectra of the films, and the acceptor binding energy is estimated to be about 125meV. The local chemical bonding environments of the phosphorus atoms in the ZnO are also identified by x-ray photoelectron spectra. Our results show direct experimental evidence that P_Zn-2V_Zn shallow acceptor complex most likely contributes to the p-type conductivity of ZnO:P films.