Hydrogenation and Annealing Effects in n-Type ZnO Bulk Samples

Abstract

Photoluminescence (PL) measurements were performed on as-grown, hydrogenated and hydrogenated and annealed n-type ZnO bulk samples in order to investigate the origins of their yellow and green emission bands. After hydrogenation, the defect-related peak at 2.10 eV was no longer present in the PL spectrum at room temperature, the peak intensity at 2.43 eV was unchanged and the intensity of the emission peak at 3.27 eV was strongly increased. These results indicate that the yellow band emission is due to oxygen vacancies because the emission peak at 2.10 eV disappears when these vacancies are passivated by hydrogen atoms. The emission peak at 2.43 eV originates from complexes between oxygen vacancies and other crystal defects. We discuss the effects of hydrogenation and annealing on the ZnO bulk samples.