Photoluminescence study of hydrogen donors in ZnO

A photoluminescence study of hydrogenated ZnO bulk crystals is presented. Two excitonic recombination lines at 3362.8 and 3360.1 meV are assigned to hydrogen shallow donors. Experimental evidence is presented that the corresponding donor to the line at 3362.8 meV, previously labeled I4, originates from hydrogen trapped within the oxygen vacancy, HO. The line at 3360.1 meV was found to be due to hydrogen located at the bond-centered lattice site, HBC. The corresponding shallow donor has an ionization energy of 53 meV.