Influence of preparation parameters on structure and optical properties of ZnO thin films

ZnO thin films were deposited on cleaned glass substrates through spray pyrolysis technique using precursor solution of zinc acetate. A comprehensive study was carried out to understand the influence of preparation parameters such as substrate temperature and precursor solution concentration on structure and optical properties of ZnO thin films. X-ray diffraction studies showed that higher substrate temperature and lower precursor solution concentration gave good crystallinity with preferred orientation along (002) direction. The films prepared at a substrate temperature of 723 K with 0.015 M precursor solution exhibited high transparency (∼95 % in visible region). The marginal increase of optical band gap energy with increase of substrate temperature was observed. However, band gap of the films decreased with the increase of solution concentration. It was observed that the grain size of the films increase with the increase of substrate temperature. The preparation conditions were optimized to obtain uniform, homogeneous and highly transparent polycrystalline ZnO thin films.