Rapid thermal plasma deposition of transparent nanocrystalline ZnO thin films and the effects of annealing

Conductive, undoped zinc oxide nanocrystalline thin film with predominant c-axis orientation is prepared on crystalline and amorphous substrates using a rapid, one-step ambient-pressure, thermal plasma chemical vapor deposition process. Nonporous and conformal zinc oxide films can be prepared at temperature as low as 160°C, with an average grain size of 25 nm. Scanning electron micrographs indicate a growth rate of 15~50 nm/min, depending on factor including source temperature, deposition temperature, and pressure. X-ray diffraction shows a predominant (002) grain orientation that is independent of the substrate's crystallinity. For films with thickness of 200 nm, the average electrical conductivity ranges from 60-910 S/m. The results demonstrate the potential of thermal plasma CVD for the rapid synthesis of conductive zinc oxide film at ambient condition.