Hard amorphous carbon studied by ellipsometry and photoluminescence

Plasma-deposited hard amorphous carbon films were studied by ellipsometry and photoluminescence. Both techniques are suited for the optical characterization of films on transparent as well as on opaque substrates. From the ellipsometric data the complex dielectric function was deduced for the energy range 1.8–5.6 eV for the as-grown as well as for thermally annealed films. In the photoluminescence spectrum both peak energy and emission intensity were found to increase (the latter by four orders of magnitude) when going from hard, strongly cross-linked films to softer, polymerlike layers.