Metal-containing diamond-like nanocomposite temperature sensors

Metal-carbon nanocomposites are characterized by a number of unique properties, perspective for the various-type sensor applications. Presented experimental data of the conductivity of amorphous tungsten- and niobium-containing carbon-silicon nanocomposite films show the possibility to design the advanced wide-range temperature sensors, which are expected to possess the chemical stability, biocompatibility, mechanical, and other properties typical for this class of materials. The investigated films were deposited onto polycrystalline substrates using combination of Plasma Enhanced Chemical Vapor Deposition (PECVD) of siloxane vapors and DC magnetron co-sputtering of metal target. The conductivity σ of the films, measured using standard 4-probe technique in the temperature range 80-400K, is characterized by the gradual decrease with temperature. The experimental σ(T) dependences are well fitted by the power-law expression, σ(T) = σ0+aTn, where σ0, a, and n are the fitting parameters dependent on the type of metal and the value of metal concentration. The electron transport mechanism in the investigated amorphous metal-containing carbon-silicon nanocomposite films is discussed in the framework of the model of inelastic tunneling of electrons in amorphous insulators in the presence of the structural transformation in the carbon-silicon host matrix. The evolution of the structure of the carbon phase by metal concentration increase was studied by Raman spectroscopy.