Characterization of ZnO thin films grown by sol-gel spin coating technique regarding precursor solution

Abstract

ZnO thin films were fabricated on glass substrates by sol-gel spin coating technique. Atomic force microscopy, X-ray diffraction and optical spectroscopy measurements were employed to analyze the effects of the precursor solution molarity. The films exhibited a hexagonal wurtzite structure with preferred c-axis orientation. The (002) peak intensity of the films decreased and full width at half maximum values reduced from 0.239° to 0.205° with increasing molarity from 0.5 M to 1.5 M. It was concluded that the molarity had affected the grain size and orientation of crystals. The grain size and the surface roughness values were 36.31 nm and 24 nm; 41.32 nm and 176 nm; 42.33 nm and 404 nm for 0.5 M, 1.0 M and 1.5 M samples respectively. The band gap values were determined as 3.28 eV, 3.23 eV and 3.16 eV, respectively for the 0.5 M, 1.0 M and 1.5 M samples.