Ultrafast Hydrogen Detection with Epitaxially Strained Thin-Film Vanadium Dioxide

Hydrogen gas (H₂) is an odorless, invisible, and explosive molecule used as a feedstock for chemical reactions required to produce a variety of high value products, such as ammonia, methanol, and semiconductors. Undetected concentrations of H₂ can quickly become dangerous to personnel and infrastructure. The characteristic thermally induced insulator-metallic transition of vanadium dioxide (VO₂), a correlated oxide with 3d¹ electronic configuration and its properties are extremely sensitive to crystalline symmetry, where recent studies have shown the electrical phase transition can be modulated with hydrogenation thus opening a pathway for novel H₂ sensing technology. Also, epitaxially strained thin films of VO₂ grown on titanium dioxide (TiO₂) restrict the structural phase change, allowing superior sensor selectivity and ultrafast response time. We report on both the electronic (X-ray photoelectron spectroscopy) and structural (X-ray diffraction) properties of thin-film VO₂ grown with magnetron sputtering to compare surface oxidation and crystallinity as a function of total growth pressure, partial oxygen pressure, growth temperature, and substrate selection, demonstrating growth-controlled optimization of the material for use in H₂ sensing devices.