Structural properties of ZnO layers deposited on glass substrates by PECVD

Abstract

Thin ZnO layers were grown by metal-organic plasma-enhanced CVD (RF - 13.56 MHz) on glass substrates without and with ZnO seed film. The properties of the ZnO layers obtained were studied in dependence of the partial oxygen pressure by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained show that by controlling the partial oxygen pressure during the layer growth one can control the crystallinity and texture of the layers obtained on pure glass substrates. It was found that ZnO layers deposited at low O2 pressure have well-developed grain structures with a predominant c-axis phase and better crystalline quality than that of the samples obtained at high partial oxygen pressure. In the presence of ZnO seed films, the formation of c-axis phase and its quality are less dependent on partial PO2. Nanorods with good alignment and orientated vertically with respect to the substrate surface can be observed in the layers deposited on glass substrates with ZnO seeds and substrate temperature of 400 °C at low content of O2 in the plasma. This behavior is interpreted in the framework of the so-called preferential nucleation and preferential grain growth.