Simulations on vanadium dioxide thin film as thermographic material

Vanadium dioxide (VO₂) has been extensively investigated due to its thermal-induced semiconductor-metal transition (SMT) at about 67°C; transition temperature can be lowered by doping. Besides the rise in electrical conductivity of up to 3-4 orders of magnitude the phase transition is followed by other changes in different physical properties, including an optical reflectance drop near to its half. Possible applications include thermally controlled electrical and optical switches. In this paper thermal simulations of a proposed thermographic arrangement are presented. The structure consists of a 100 nm thick VO₂ thin film deposited on the passivated surface of a silicon chip. The goal of these simulations is to predict the acquirable resolution of the proposed method. Abstract heat sources are defined on the silicon surface and the temperature of the thin film is calculated. Thermal mapping could be performed by optical observation of the isotherm at transient temperature, while the dissipation and the cooling of the chip is swept. Possible benefits of the proposed method include the simple and reliable use of the once-deposited solid phase film, maintaining a few micron resolution, similar to liquid crystals, as predicted in earlier electro-optical measurements.