Effect of Plasma Process on the WO<sub>3</sub> Thin Films

O 2 plasma treatment induces a transformation in the structure of WO 3 thin films, converting them into a crystalline structure. Amorphous WO 3 thin films were deposited on silicon produced by pulsed DC reactive magnetron sputtering at room temperature. The as-deposited films were treated with oxygen plasma powered by an RF generator. During the plasma treatment, the pressures were set at 1 x 10 -1 to 1x 10 -2 mbar, while the RF supplied powers at 100 W and 200 W. The effects of plasma treatment induced modifications of structure and physical properties of WO 3 thin films. Several techniques were used to characterize microstructure, phase composition and surface morphology of the films including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). An RF generator powered the O 2 plasma treatment on the as-deposited films. During the plasma treatment, the pressures were set at 1.0x10 - 1 and 1.0x10 -2 while the RF powers was supplied at 100 and 200 watt, respectively. The film's crystal structure changed at 200W plasma power and 1 x 10 -2 mbar operating pressure. The O 2 plasma treatment significantly changed the thickness of the films, probably as a result of changes in the packing density and surface etching. The experimental results suggest that the plasma treatment excitation process after crystallization can transform the films' amorphous structure into a crystalline structure.