Effect of chlorine ion concentration on morphology and optical properties of Cl-doped ZnO nanostructures

Effect of Cl−1 concentration on morphology and optical properties of Cl-doped ZnO nanostructures was studied. The Cl-doped ZnO nanostructures and undoped ZnO microstructures were grown on Si(1 1 1) substrates using a physical vapor deposition method. The ZnO nanostructures have been doped with different concentrations of chlorine. The Cl-doped ZnO nanostructures with 6% atom Cl, showed a nanodisk morphology with a hexagonal shape, while the Cl-doped ZnO nanostructures with 9% atom Cl, exhibited a stacked nanoplate morphology with smaller thickness in comparison to the Cl-doped ZnO nanodisks. In addition, with increasing Cl content to 13%, morphology of the products changed to more stacked nanoplates with nanoflakes morphology. X-ray diffraction results clearly showed a hexagonal structure for the all samples. Raman spectroscopy results showed a strong crystalline quality for the undoped ZnO microdisks and Cl-doped ZnO nanodisks; while these results indicated a weak crystalline quality for the Cl-doped ZnO nanoplates and nanoflakes. Photoluminescence (PL) studies also confirmed the Raman results and it exhibited a lower optical property for the Cl-doped ZnO nanoplates and nanoflakes in comparison to the undoped ZnO microdisks and Cl-doped ZnO nanodisks. Furthermore, the UV peak of the Cl-doped ZnO nanostructures was blue-shifted with respect to that of the undoped ZnO.