Improved optical transparency of calcium-doped ZnO thin films

Abstract

ZnO thin films with various Ca-doping contents were produced by spray pyrolysis. X-ray diffraction results showed that all samples had a hexagonal structure. Morphological analysis indicated that all films had granular topography. the best transparency was obtained for 2 at.% Ca-doped ZnO samples. Band gap of ZnO thin films was found to be 3.22 eV and didn'tchange with increasing of Ca-doping. Photoluminescence data indicated that all samples had four emission peaks. Electrical measurements revealed that Ca-doping resulted in a gradual improvement of carrier density and consequently a decrement of resistivity, which is important for application areas in opto-electronics.