ZnO nanostructured thin films grown by pulsed laser deposition in mixed O2 / Ar background gas

We report on the properties of ZnO nanostructured thin films grown on either bare or gold patterned a-plane sapphire substrates. The pulsed laser deposition technique was used to deposit all the films at a temperature of 700 C in a mixture of oxygen and argon under a total pressure of 35 Pa. SEM surface characterizations typically showed pyramidal nanostructures with hexagonal symmetry and a coverage density strongly dependent on the O₂ partial pressure. For the patterned samples, wall-like structures of nanoneedles were observed. For all samples, x-ray diffraction results confirmed the high crystalline quality of the nanostructures, with the rocking curve widths of the (0002) reflection as low as 0.09. Similarly, photoluminescence results at room temperature testified to the high optical quality of the material.