Influence of substrate temperature on structural and optical properties of RF sputtered ZnMnO thin films

The ZnMnO thin films were deposited on glass substrates by radio frequency magnetron sputtering method. The properties of ZnMnO thin films were investigated by high-resolution x-ray diffractometer (HRXRD), atomic force microscopy (AFM), UV-Vis spectrometer and room temperature photoluminescence (PL), under the influence of substrate temperature. The substrate temperature was varied from 300, 400 and 500$^\circ$C. With increasing the substrate temperature, the structure of the films changed from cubicto hexagonal. The cubic ZnMnO thin films grown along [210] direction, while the hexagonal ones grown along [002] direction. The changes in surface morphology provided a proof on the structural transition. Also, decrease and increase of optical band gap is associated with cubic or hexagonal structure of the films.