W-doped monoclinic vanadium dioxide VO2(M) thin films with various W contents were successfully deposited by magnetron sputtering method. As-deposited films consisted of multilayers composed of VO2/W bilayers. Further annealing at 500 degrees C under Argon for 1 h led to crystallized and homogeneous V1-xWxO2 +/-delta films. 200 nm films were characterized at room temperature by Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Besides, the films were analyzed by temperature-dependent infrared transmittance in the wavelength region 2-25 mu m and the effects of W doping on thermochromic properties of VO2 were studied. The results show that the transition temperature gradually decreases with increasing W content. A transition temperature of 21 degrees C with a high infrared transmittance modulation (approximate to 68%) was finally achieved with a W-doping level of 2.7 at.% which may indicate a strong potential for applications in optical devices as functional materials. (C) 2020 Elsevier B.V. All rights reserved.
From multilayers to V1-xWxO2 +/-delta films elaborated by magnetron sputtering for decreasing thermochromic transition temperature
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