Formation and transmittance property of WO3 films deposited by mid-frequency dual-target magnetron sputtering

Amorphous WO3 films were prepared by mid-frequency dual-target magnetron sputtering. X-ray diffraction, energy dispersive X-ray microanalysis, scanning electron microscopy and spectrophotometer were used to characterize their structure, morphology, composition and transmittance properties. The effects of oxygen content and heat treatment temperature on the electrochromism were studied. The results show that the as-deposited films are amorphous. WO3 crystalline is formed when annealing temperature is up to 300–400 °C. The films deposited at higher oxygen content show a good electrochromic property after annealing at 200 °C.