Bath Temperature Effect on c-axis Preferred Orientations and Band Gap of Semiconductor ZnO Thin Films

Abstract

Semiconductor ZnO thin films were deposited via chemical bath deposition technique (CBD) on glasssubstrates at varying temperatures (75°C-90°C). Influence of bath temperature on c-axis preferredorientations of ZnO thin films were examined. X-ray diffraction (XRD) results proved that thin filmsdeposited at 80°C and 85°C bath temperature have a preferred orientation towards (011) peak. The preferredorientation changed towards (010) peak when the bath temperature increased to 90°C. Field Emission ScanningElectron Microscope (FESEM) images proved that ZnO thin film structure was formed by flower-like nanorods. Inthe thin films produced at 80°C and 85°C, the alignment of the nanorods was vertical, while in the films produced at90°C, the nanorods mostly formed horizontally. These FESEM images also proved that the preferential orientationhas changed from (011) to (010). Effects of bath temperature on band gap of semiconductor ZnO thin films wereinvestigated by UV-Visible Spectrophotometer. ZnO thin films band gap value increased to 3.37 eV as the bathtemperature increased to 85°C. When the bath temperature increased to 90°C the band gap value strongly decreasedto 3.24 eV.