Effect of precursor ratio on the structural properties of ZnO thin films deposited by low pressure MOCVD

The effect of precursor ratio (H ₂O/DEZ) on the texture orientation, surface morphology, optical transparency and electrical resistivity of ZnO thin films deposited by MOCVD was investigated. Deposition temperature and pressure were fixed at 120 °C and 0.67 torr, respectively. The precursor ratio was varied between 0.1 and 4. It was found that the texture orientation changed from 〈0002〉 to 〈1120〉 with increase of the precursor ratio. 〈1120〉 textured film shows well facetted tetrapod like rough surface morphology, which scatters the incident light very effectively. The electrical resistivity was in the range of about 0.1 Ω cm in the undoped state, which was found to decrease with increase of the film thickness and decrease of the precursor ratio.