Electrical conductivity of as‐prepared and annealed amorphous hydrogenated carbon films

The electrical conductivity of a‐C:H films prepared by rf glow discharge decomposition of methane at different rf power densities was studied in as‐prepared and annealed films. The observed behavior in the conductivity as a function of heat treatments can be understood in terms of the structural changes induced by the annealing. For heat treatment temperatures up to 400 °C, no significant structural changes are observed, as determined by Raman and photoluminescence measurements. This is in agreement with an approximately constant room temperature conductivity in this temperature range. For higher annealing temperatures, the sudden increase in the conductivity, over ten orders of magnitude, can be understood in terms of dehydrogenation followed by the nucleation and growth of conductive graphite particles.