Electrical and Infrared Optical Properties of Vanadium Oxide Semiconducting Thin-Film Thermometers

A synthesis method has been developed for preparation of vanadium oxide thermometer thin film for microbolometer application. The structure presented is a 95-nm thin film prepared by sputter-depositing nine alternating multilayer thin films of vanadium pentoxide (V2O5) with thickness of 15 nm and vanadium with thickness of 5 nm followed by postdeposition annealing at 300°C in nitrogen (N2) and oxygen (O2) atmospheres. The resulting vanadium oxide (VxOy) thermometer thin films exhibited temperature coefficient of resistance (TCR) of −3.55%/°C with room-temperature resistivity of 2.68 Ω cm for structures annealed in N2 atmosphere, and TCR of −3.06%/°C with room-temperature resistivity of 0.84 Ω cm for structures annealed in O2 atmosphere. Furthermore, optical measurements of N2- and O2-annealed samples were performed by Fourier-transform infrared ellipsometry to determine their dispersion curves, refractive index (n), and extinction coefficient (k) at wavelength from 7000 nm to 14,000 nm. The results indicate the possibility of applying the developed materials in thermometers for microbolometers.