Zn and W Co-doped VO 2 -Based Thin Films Prepared by DC Magnetron Sputtering: Improved Luminous Transmittance and Reduced Transition Temperature

Un-doped VO 2 , tungsten (W)-doped VO 2 , and W/Zn co-doped VO 2 thin films were successfully prepared by two DC magnetron sources and co-sputtered at a substrate temperature of 425°C onto soda lime glass substrates. The aim was to find whether co-doping of VO 2 films with W and Zn could decrease the transition temperature and increase both luminous transmittance and solar transmittance modulation (Δ T sol ) of VO 2 -based thin films. The thin films were characterized by x-ray diffraction, atomic force microscopy, Rutherford backscattering spectroscopy, the two-point probe technique, Hall effect measurement system, and a PerkinElmer Lambda 1050+ UV/VIS/NIR) spectrometer. This work revealed that a controlled amount of Zn in the W-doped VO 2 films showed solar transmittance modulation of 4%. It further improves the luminous transmittance to ~ 46%, lowering the phase transition temperature to below 27°C, compared to un-doped VO 2 and W-doped VO 2 thin films at 64.8°C and 44°C, respectively. These results show that the combined effect of W and Zn doping on VO 2 films has the potential to make the films useful for smart window applications.