Pressure effect on optical and structural properties of ZnMnO thin films grown by pulsed laser deposition

Abstract

Zn0.95Mn0.05O thin films were deposited on Si substrate by pulsed laser ablation technique under different oxygen pressure. The structural and optical properties of the films were analyzed as a function of the oxygen gas pressure. The Mn concentration and the substrate temperature of the thin films were kept constant at 5 wt% and 200°C respectively. X-ray diffraction technique (XRD), atomic force spectroscopy (AFM), raman spectroscopy and UV-Vis were employed to characterize the optical properties and the crystalline structure of the films. The diffraction patterns revealed that the Mn0.05Zn0.95O thin films were polycrystalline with the wurtzite hexagonal structure of ZnO and highly oriented in c-axis direction, without any secondary phases. The average energy band gap of the films was evaluated around 3.23-3.56 eV. Raman spectrum showed E2 (low) mode of ZnO structure shifted to red and increased its FWHM.