Spatially resolved optical properties of ZnO sub-microstructures on a graphene monolayer

We investigated the carrier-gas flows-ratio-dependent structure evolution of ZnO submicrostructures grown on a graphene/SiO₂/Si substrate without a catalyst or seed layer by using thermal chemical vapor deposition. The surface morphology and the crystalline quality of the ZnO sub-microstructures measured by using field-emission scanning electron microscopy, X-ray diffraction, and Raman spectroscopy showed a clear dependence on the carrier-gas flow ratio. The spatially resolved photoluminescence property of the ZnO structure was investigated by using confocal scanning photoluminescence microscopy, and ZnO grown at an oxygen flow rate of 50 sccm showed relatively good optical properties.