Effect of nanocrystalline phase on the electrical conductivity of amorphous tantalum-containing silicon-carbon films

We have studied the effect of metal concentration on the electrical conductivity of tantalum-containing silicon-carbon nanocomposite films. The results demonstrate that carrier transport in the films follows different mechanisms at low and high metal concentrations. When the concentration of the conducting nanocrystalline tantalum carbide phase is under 28 at %, conduction is due to hopping. Conducting-phase concentrations from 28 to 34 at % correspond to a percolation threshold. At higher tantalum carbide concentrations, conduction is through the tantalum carbide nanocrystals. The effect of heat treatments on the electrical conductivity of the material is analyzed.