Electronic transport in amorphous carbon nitride (a-CNx:H) and carbon oxide (a-COx:H) films

The dielectric properties of a-CNx:H and a-COx:H thin films have been investigated using ohmic σ(T) and field-dependent σ(F) electrical conductivity measurements. A lower density of electronic states in carbon oxides has been inferred from the Ln(σ)≈T−1/4 behavior, consistent with a hopping mechanism. The dielectric constant ε values deduced from the Poole–Frenkel field-dependence are found to decrease (increase) with increasing oxygen (nitrogen) content. Using refractive index values obtained from ellipsometry, a good agreement between ε and n2 is found for the oxygen-rich (18–20%) alloys, having values of ε∼1.9–2.3, which could be considered as a new low dielectric constant material.