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 aa-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.