Structural, Optical, and Luminescence Properties of Reactive Magnetron Sputtered Tungsten Oxide Thin Films

Tungsten oxide (WO3) thin films were deposited on to unheated Corning glass and silicon substrates by RF magnetron sputtering of metallic tungsten target at various oxygen partial pressures in the range – Pa. The influence of oxygen partial pressure on the structure and surface morphology and the optical and photoluminescence properties of the films were investigated. X-ray diffraction studies revealed that the deposited films were amorphous in nature. Fourier transform infrared transmission spectra confirmed that the presence of stretching vibration of W-O-W and deformation of W-O bonds related to the WO3. The optical transmittance of the films at wavelengths >500 nm increased from 62% to 85% with the increase of oxygen partial pressure. The optical band gap of the films increased from 3.00 to 3.14 eV and the refractive index of the films decreased from 2.26 to 2.08 with the increase of oxygen partial pressure from to  Pa, respectively. The photoluminescence studies indicated that the intense blue emission which was assigned to band-to-band transition was observed at oxygen partial pressure of  Pa.