Structural transformation and functional properties of vanadium oxide films after low-temperature annealing

A two-step method is offered for the synthesis of vanadium oxide films to purposely change their functional properties. Vanadium oxide films were deposited on glass and silicon substrates by using magnetron sputtering of the vanadium target at various substrate temperatures (180-500 °C). During deposition, the substrate temperature predetermines structural and functional properties of the films after their following low-temperature (250-350 °C) annealing. In the films deposited at low substrate temperatures (200-220 °C), after low-temperature annealing there formed are flat crystallites of vanadium dioxide with lateral sizes 1 to 2 μm, which provides a high thermochromic effect. In the films deposited at temperatures of 250-300 °C, during the following low-temperature annealing the microcrystalline mixture of different vanadium oxides (50-150 nm) is formed, which provides a high value of the thermal coefficient of resistance for these films (7%/K). The low temperature annealing practically does not change the properties of films deposited at temperatures of 450-500 °C.