CHEMICAL AND OPTICAL PROPERTIES OF MNO2 THIN FILMS PREPARED BY REACTIVE EVAPORATION OF MANGANESE

Abstract

Thin films of manganese oxide were deposited by thermal reactive evaporation of pure manganese. The films were deposited at room temperature under various oxygen partial pressures. Structural analyses were performed by X-ray diffraction and atomic force microscopy. The films were polycrystalline and the surface roughness of the films was oxygen partial pressure-dependent. Chemical analysis, studied by x-ray photoelectron spectroscopy, exhibited the control of stoichiometry in the films by varying the oxygen partial pressure, where fully oxidized MnO2 films were obtained at higher oxygen partial pressures. Optical measurements revealed a slight decrease in the transmittance of the films prepared at higher oxygen partial pressures. Gradual increase in the direct band gap of the films with oxygen partial pressure was noted. Based on the structural and chemical characterizations, the optical properties (refractive index and extinction coefficient), of the stoichiometric MnO2 film were investigated.