Effects of electron-beam irradiation and substrate temperature on the physical properties of evaporated a-Si:C thin films

Thin films of a-Si:C have been prepared by thermal evaporation from resistive- and rf-induction-heated carbon crucibles. Samples were prepared with and without electron-beam irradiation of the substrate during deposition, and the resulting film properties (electrical and optical) were measured. Reference samples prepared with substrate temperatures from 150 to 250 °C and annealing temperatures from 200 to 250 °C had very similar film properties. The use of vitreous carbon instead of compressed carbon for the crucibles reduced the carbon content by about 30% and the oxygen content of the films by more than a factor of four. Electron-beam irradiation of the purer films produced a tenfold decrease in the conductivity at room temperature and an increase of the high-temperature activation energies compared with the reference samples.