DIAMOND-LIKE PROPERTIES OF AMORPHOUS-CARBON AND HYDROGENATED AMORPHOUS-CARBON THIN-FILMS

Films of amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) have been prepared by r.f. magnetron sputtering of a graphite target in atmospheres without and with hydrogen respectively. These films have been studied by optical, electrical and electron spin resonance measurements. The conductivity and the optical absorption coefficient values were found to be similar for the two materials. The only relevant difference was detected in the volume density of spins. It was found to be around 10(21) cm-3 for a-C and below 10(20) cm-3 for a-C:H samples. It is shown that diamond-like a-C, having similar properties to a-C:H, can be obtained by means of this technique. As a consequence, hydrogen plays only an indirect role in determining the relevant optical and electrical parameters. However, the hydrogenated material is less defective.