Optical Absorption and Electrical Conductivity of Amorphous Carbon Thin Films from Camphor: A Natural Source

Thin films of carbon have been deposited on n-type single-crystal silicon and quartz substrates by simple ion beam sputtering of camphoric carbon, obtained from camphor, a natural source. Optical absorption coefficients of 104–105 cm-1 have been obtained for the as-deposited and annealed films and the absorption coefficient increased upon annealing. The optical band-gap energy of the as-deposited camphoric carbon thin film derived from optical absorption measurements is 0.5 eV. Effects of annealing on various optical and electrical properties are studied, in light of the semiconducting nature of these films, through the electrical conduction mechanism. The results obtained are discussed and compared with the literature.