Deposition Niobium Oxide Optical Thin Films by Low Frequency Reactive Magnetron Sputtering

Niobium oxide optical thin films have been prepared by low frequency reactive magnetron sputtering system. The microstructure, morphology and optical properties of the films were investigated by X-ray diffraction, field-emission scanning electron microscope and optical transmittance. Niobium oxide films are amorphous and the surface is very smooth. Additionally, the refractive index of the films at wavelength of 550 nm is 2.264 and extinction coefficients are lower than 10~(-3) when the wavelengths are larger than 400 nm. The optical band gap is 3.49 eV. The prepared films are good for optical applications.