Deposition of ZnO thin films on Si by RF magnetron sputtering with various substrate temperatures

Undoped ZnO thin films were successfully deposited on Si substrates by RF magnetron sputtering with different substrate temperatures. The dependence was systematically investigated the structural, morphology, chemical state and optical properties of ZnO thin films. Crystal quality, growth orientation and optical properties of ZnO thin films were improved at proper substrate temperature (450 °C) whereas were deteriorated at higher temperature (600 °C). X-ray photoelectron spectroscopy showed that proper substrate temperature promoted the formation of Zn–O bonding, resulting in an improvement of film quality, while higher temperature decreased the formation of the Zn–O bonding and increased the oxygen vacancy due to formation of an amorphous SiO₂ layer at the interface of ZnO and Si, resulting in a degradation of film quality. Moreover, the amorphous SiO₂ layer is formed by oxygen related to the Zn–O bonding, mainly. Therefore, the experimental results indicate that the substrate temperature plays an important role in the deposition of ZnO film on Si substrate and needs to be carefully selected to suppress a formation of an amorphous SiO₂ layer.