Distribution pattern and allocation of defects in hydrogenated ZnO thin films†
A polycrystalline ZnO thin film prepared by atomic layer deposition was annealed in hydrogen at 10 bar and 350–450 °C. Hydrogenation induced simultaneous formation of oxygen and zinc vacancies whose concentrations were closely related to the temperature of treatment. Spatial distributions of these defects were analyzed by photoluminescence confocal mapping which revealed that their localized appearances are linked to each other. It was also demonstrated that nanomechanical mapping of elastic modulus distribution could be used to assess the allocation of accumulated defects on the topmost surface of ZnO with a depth resolution of only several atomic layers. The higher the temperature of hydrogenation, the higher the concentration, and more uniform the distribution of surface defects. In addition, the correlation between the surface morphology and the accumulated defects was established.