Deposition of ZnO Thin Films by an Atmospheric Pressure Plasma Jet-Assisted Process: The Selection of Precursors

The deposition ZnO thin films using an atmospheric pressure plasmas jet (APPJ)-assisted process using different precursors is presented. In this process, nebulized salt solutions droplets or precursor vapor were injected into the downstream of the APPJ to perform deposition of ZnO thin films. Zinc chloride (ZC)-, zinc acetate (ZA)-, and zinc nitrate (ZN)-containing solution and zinc acetylacetonate (ZAA) were precursors tested. For all precursors tested, formation of ZnO was observed based on X-ray diffraction analysis. ZC, however, was the only precursor that yields smooth films, which yields average transmittance in the visible wavelength range well >70%. When ZN, ZA, and ZAA were used as the precursors, rather rough films were obtained due to the fact that these precursors decomposed and formed ZnO readily upon heating. A high rate of volume nucleation, therefore, occurs in the gas phase. The above observation serves as the guideline for the selection of precursors for APPJ-assisted thin-film deposition processes.