Fabrication and structural characterization of hybrid nanostructures of ZnO/Si

ZnO/SiO _x films grown on Si (100) wafers by radio-frequency sputtering and ion beam sputtering, respectively were annealed at 1100 °C for 20 min to form hybrid nanostructures of ZnO/Si. As proven by cross-sectional high-resolution transmission electron microscopy (HRTEM) images annealing causes the ZnO/SiO _x double layer to transform into a hybrid nanostructure mixed with ZnO nanocrystals (NCs) and Si NCs within SiO ₂ Scanning electron microscopy, plan-view HRTEM and scanning-mode TEM images of the sample surfaces exhibit leaf-vein-like nanostructures composed of nanoscale SiO ₂ streaks and ZnO NCs. As x increases, the size of the Si NCs in the hybrid nanostructures decreases more steeply than it does in bare SiO _x layers The intensities of the O K-edge near-edge X-ray absorption fine-structure features increase as x increases, reflecting an increase in the unoccupied surface states of ZnO NCs.