Structural properties of zinc oxide deposited using atmospheric pressure combustion chemical vapour deposition

• Columnar growth structures of ZnO by CCVD were observed.
• The presence of polycrystalline ZnO with (002) as main orientation was confirmed.
• Initial particles significantly differ from crystallite sizes of the resulting films.
• The films show an excess of Zn with a Zn-to-O ratio of around 1.7.

In this study the deposition of thin zinc oxide (ZnO) films under atmospheric pressure conditions was investigated. The deposition technique applied was combustion chemical vapour deposition (CCVD), at which a propane–air mixture was combusted in a burner. Dissolved zinc nitrate was used as precursor, which was guided as aerosol droplets by the processing gas flow directly into the reaction zone. Fundamental investigations were performed to form undoped ZnO. The structural properties of the films were analysed in dependence of the substrate temperature during the coating process.The presence of crystalline ZnO structures was proved and differences in film growth and crystallite sizes are revealed. Additionally, the particles generated by the CCVD-flame are characterised. The thin films showed a slight excess of Zn and several states of binding energy could be observed by fitting the core level spectra. Scanning and transmission electron microscopy also indicated ordered structures and additionally different orientations of crystallites were observed.