High-performance thermal sensitive W-doped VO2(B) thin film and its identification by first-principles calculations

Abstract VO 2 (B) is currently a preferred phase structure for the application as bolometer material, which, however, suffers from low temperature-coefficient-of-resistance (TCR) values and large resistances. Here we present the combined experimental and first-principles calculations study on both doped and undoped VO 2 (B) thin films enabling us to attain high TCR (−3.9%/k) and suitable square-resistance (32.7 kΩ) by controlled W doping employing the widely used magnetron sputtering technique. The TCR value is 50% larger than reported ones at the similar resistance. The underlying microscopic mechanism for the performance improvement was studied and results indicated that the introduction of extra electrons and the variation in the band structure resulting from the incorporation of W 6+ ions in the VO 2 (B) crystal lattice contribute to the enhancement of the electronic conductivity. Moreover, the special two-dimensional octahedral structure of monoclinic ( C 2/m) B-phase VO 2 favors the strain control with W-doping for achieving a large TCR, which overcomes the analogous predicament between the high conductivity and large TCR generated by dopants in the M-phase VO 2 . The present findings provides a facile and simple pathway for the design and fabrication of high performance W-doped VO 2 (B) thin films rendering superior optical and electrical properties for its wide applications in thermo-opto-electro sensing devices.