Effects of pressure and substrate positions on ZnO nanostructures during thermal evaporation of Zn Metal

ZnO nanostructures were prepared using a Zn metal source by the thermal evaporation process. The shapes of the ZnO nanostructures were changed depending on pressures and distances from the metal source in a tube furnace. One-dimensional nanowires with high crystallinity and density were formed at an ambient atmospheric pressure, while three-dimensional hollow structures resulted at low pressure. The structural morphology, phase composition, and crystallinity of ZnO were examined by the SEM, TEM and XRD. The defect emission peaks originated from the remaining Zn metal and oxygen partial pressure were investigated by the PL analysis. The relationship between the nanostructural change and different pressures (or remaining Zn metal) is explained as well