Structure and optical characterization of ZnO-Sn thin films

ZnO-Sn thin films were prepared and deposited on p-type silicon substrate using sol-gel method, followed by spin coating technique. The solution consists of zinc acetate dihydrate, tin chloride, 2-methoxyethanol and monoethanolamine which acted as a precursor, dopant, solvent and stabilizer respectively. Effect of different Sn/ZnO molar ratios on the crystallinity and surface morphology of thin films were studied in this research. The molar ratios of Sn/ZnO were maintained to 1%, 3% and 5%. The ZnO-Sn thin films were heated on hotplate at 300 °C for 20 min and then sintered at 500 °C for 2 hrs. The effect of different molar ratios of Sn/ZnO on the surface morphologies and crystalline structure properties of ZnO-Sn thin films were examined using atomic force microscopy (AFM), X-ray diffraction (XRD). XRD patterns showed that all doped films have (101) as the preferred orientation. The optical properties showed that the film with Sn/ZnO molar ratio of 3% having the optical transmittance of more than 80%, which was more than other doped films of our experiment. The FTER spectrum shows that at Sn/ZnO molar ratio of 5%, the intensity of ZnO peak is very weak and that may be due to the incorporation of Sn with the ZnO structure.