Study of the structure, optical properties, surface morphology and topology of ZnO thin films grown by sol–gel on silicon substrates

Abstract

Polycrystalline visible light photoluminescent zinc oxide (ZnO) thin films have been grown on silicon substrates by the dip immersion sol–gel technique at low sintering temperature. The optical properties of the films were analyzed by UV–vis spectroscopy. The structural properties were measured with x-ray diffraction. The results show that the films are polycrystalline and have hexagonal wurtzite structure. The estimated band gap of the samples by UV–vis absorption spectroscopy is in good agreement with the value measured by UV–vis reflectance spectroscopy and is near 3.2 eV. The surface topography was observed with atomic force microscopy. The morphology of the samples was analyzed by scanning electron microscopy. Energy dispersive x-ray spectroscopy was used to make chemical composition measurements, the results indicate that the sample is stoichiometric. The photoluminescence (PL) spectroscopy shows a strong band in the blue–green region of the spectrum, which makes these films interesting to optoelectronic applications.