OPTICAL AND LUMINESCENCE PROPERTIES OF POLYMER-LIKE A-C-H FILMS DEPOSITED IN A DUAL-MODE PECVD REACTOR

Butane has been decomposed in the post-discharge of a helium-argon mic rowave plasma, assisted by a radiofrequency (rf) plasma. The ion bomba rdment on the substrate, monitored by the rf power, is found to contro l the optical and luminescence properties of hydrogenated amorphous ca rbon (a-C:H) thin films: the extinction coefficient of a-C:H increases with rf power while the photoluminescence efficiency decreases by thr ee orders of magnitude. The parametrization of the dielectric function , using a three-phase effective medium approximation, is discussed in relation to the expected size effects on the dielectric function of th e pi-bonded clusters.