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<p>This work reports the fabrication and characterization of high-quality tungsten-doped vanadium dioxide (W<sub><i>x</i></sub>V<sub>1-<i>x</i></sub>O<sub>2</sub>, <i>x</i> = 0 ~ 3 at. %) by thermal oxidation of sputtered tungsten-vanadium alloyed thin films with different atomic percentages and high-temperature annealing in an extremely low oxygen atmosphere (5&#xa0;ppm to 20&#xa0;ppm) along with reduction of surface over-oxides in high vacuum (1&#xa0;mPa). Oxidation parameters such as temperature, time and nitrogen purging rate are first optimized for obtaining high-quality undoped VO<sub>2</sub> thin film. Insulator-to-metal (IMT) phase transition behavior of VO<sub>2</sub> thin films fabricated in a low-O<sub>2</sub> environment is characterized with temperature-dependent spectral infrared transmittance and electrical resistivity measurements, where there is 15&#xa0;% higher infrared transmittance change and additional 1 order change in resistivity in comparison with VO<sub>2</sub> thin films fabricated in a O<sub>2</sub>-rich environment. Grazing angle X-ray diffraction scan confirms no presence of higher oxides in the VO<sub>2</sub> oxidized in low-O<sub>2</sub> environment, which improves its quality significantly. Comprehensive studies on thermal annealing and vacuum reduction for tungsten-doped VO<sub>2</sub> thin films are also carried out to find the optimal fabrication conditions. With the tungsten at. % measured by X-ray photoelectron spectroscopy, the optimal WVO<sub>2</sub> thin films fabricated through this streamlined oxidation, annealing and reduction processes in extremely low-O<sub>2</sub> furnace environment exhibit lowered IMT temperature at − 23&#xa0;°C per at.% of tungsten dopants from 68&#xa0;°C without doping. This low-cost and scalable fabrication method could facilitate the wide development of tunable WVO<sub>2</sub> coatings in thermal and energy applications.</p>

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Thermal Radiative Properties of Tungsten-Doped Vanadium Dioxide Thin Films Fabricated in an Extremely Low-Oxygen Furnace Environment

  • 期刊论文

  • 发表日期：

    2025年11月18日

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  • Vishwa Krishna Rajan,
  • Ken Araki,
  • Robert Y. Wang,
  • Liping Wang

摘要

This work reports the fabrication and characterization of high-quality tungsten-doped vanadium dioxide (WxV1-xO2, x = 0 ~ 3 at. %) by thermal oxidation of sputtered tungsten-vanadium alloyed thin films with different atomic percentages and high-temperature annealing in an extremely low oxygen atmosphere (5 ppm to 20 ppm) along with reduction of surface over-oxides in high vacuum (1 mPa). Oxidation parameters such as temperature, time and nitrogen purging rate are first optimized for obtaining high-quality undoped VO2 thin film. Insulator-to-metal (IMT) phase transition behavior of VO2 thin films fabricated in a low-O2 environment is characterized with temperature-dependent spectral infrared transmittance and electrical resistivity measurements, where there is 15 % higher infrared transmittance change and additional 1 order change in resistivity in comparison with VO2 thin films fabricated in a O2-rich environment. Grazing angle X-ray diffraction scan confirms no presence of higher oxides in the VO2 oxidized in low-O2 environment, which improves its quality significantly. Comprehensive studies on thermal annealing and vacuum reduction for tungsten-doped VO2 thin films are also carried out to find the optimal fabrication conditions. With the tungsten at. % measured by X-ray photoelectron spectroscopy, the optimal WVO2 thin films fabricated through this streamlined oxidation, annealing and reduction processes in extremely low-O2 furnace environment exhibit lowered IMT temperature at − 23 °C per at.% of tungsten dopants from 68 °C without doping. This low-cost and scalable fabrication method could facilitate the wide development of tunable WVO2 coatings in thermal and energy applications.