Investigation of the electrical transport mechanism in VOx thin films

Vanadium oxide VO2 is a material that transforms from semiconductor to a metal state at a temperature of 67 °C. This phase transformation is accompanied by a dramatic change in its electrical and optical properties. Therefore, vanadium oxide thin films are most attractive for switching applications. Non-stoichiometric thin films of VOx, including VO2, also present such thermal response.This paper presents the optical and electrical properties of vanadium oxide thin films deposited by vacuum thermal evaporation of a metal vanadium with follows oxidation. We have studied the electro-physical behavior of these films during their phase transition. It was shown that the electrical transport mechanism of the obtained vanadium oxide films differ in low and high electrical fields. In low electrical fields, conductivity is obtained by the Schottky transport mechanism, whereas in high electrical fields, conductivity ranges from Ohmic, for medium fields, to Poole–Frenkel for higher fields. Also, FTIR and near IR reflectance characteristics of the obtained films are presented.

► VOx films behavior depends on the presence and quantity of crystalline VO2 phase.
► FTIR and near IR reflectance spectrums enable observation of crystalline VO2 phase.
► Conductivity mechanism of VOx films depends on the applied electrical field.