Structural, optical and electrical properties of post annealed K-doped ZnO films for optoelectronics applications

Effect of annealing temperature on the optical, structural and electrical properties of K doped ZnO films have been studied out. K doped ZnO thin films were prepared on glass substrate by sol-gel spin coating technique. The influence of temperature on crystal size, transparency, band gap and conductivity were observed. XRD pattern reveals an increase of the crystallite size with annealing temperature. Crystallinity of the deposited films was found to be improved with annealing temperature. It was observed that the average transmittance decreases with increase in annealing temperature. Band gap have been estimated from absorption coefficient, which results decrease in band gap from 3.30 eV to 3.264 eV, which signifies the results of I-V characteristics with increase in conductivity. Photoluminescence (PL) spectra are dominated by a high strong intensity peak at 398 nm followed by a low intensity peak at 467 nm. All the results of this study lead to the applicability of KZnO as a transparent conducting material for optoelectronic devices.