Electron transport in W-containing amorphous carbon-silicon diamond-like nanocomposites

The electron transport in amorphous hydrogenated carbon-silicon diamond-like nanocomposite films containing tungsten over the concentration range 12-40 at.% was studied in the temperature range 80-400 K. The films were deposited onto polycrystalline substrates, placed on the RF-biased substrate holder, by the combination of two methods: PECVD of siloxane vapours in the stimulated dc discharge and dc magnetron sputtering of tungsten target. The experimental dependences of the conductivity on the temperature are well fitted by the power-law dependences over the entire temperature range. The results obtained are discussed in terms of the model of inelastic tunnelling of the electrons in amorphous dielectrics. The average number of localized states (n) in the conducting channels between metal clusters calculated in the framework of this model is characterized by the non-monotonic dependence on the tungsten concentration in the films. The qualitative explanation of the results on the basis of host carbon-silicon matrix structural modifications is proposed. The evolution of the carbon-silicon matrix microstructure by the increase in the tungsten concentration is confirmed by the Raman spectroscopy data.