Metal–insulator phase transition in tungsten-doped vanadium dioxide thin films

The electrical conductivity of thin polycrystalline V$_{(1-x)}$W$_{x}$O$_{2}$ has been studied in a wide temperature range, which covers the regions of both the metallic and insulator phases. An increase in the tungsten concentration is shown to shift the metal–insulator phase transition toward lower temperatures, while the temperature range of the coexistence of the phases monotonically increases as the impurity concentration increases. The temperature dependence of the conductivity of the insulator phase of V$_{(1-x)}$W$_{x}$O$_{2}$ is explained using the hopping conduction model that takes into account the influence of thermal vibrations of atoms on the resonance integral. Parameter $\varepsilon$ in the dependence on the level of doping VO$_2$ has been calculated.