Crystallite size dependence of band gap energy for electrodeposited ZnO grown at different temperatures

Zinc oxide thin films were grown by potentiostatic electrodeposition at different bath temperatures (62–89 °C, and −1 V vs. SCE) from a 0.1 M Zn(NO3)2 solution. X-ray diffraction (XRD) shows there is crystallite size enlargement as bath temperature increases. The band gap energy values, determined from optical reflectance spectra, are between 3.2 and 3.3 eV, decreasing when the bath temperature increases. A quantum size effect is deduced from the correlation between the band gap energy and the crystallite size.