Freestanding diamond thin films grown on glassy carbon substrates

During our recent efforts to grow polycrystalline diamond thin films on glassy carbon substrates using microwave-assisted chemical vapor deposition, we have reproducibly observed that a freestanding, polycrystalline diamond film is formed and can be lifted from the surface easily. The glassy carbon surface, on which the diamond films form, is gray in color (as opposed to the normal mirrorlike finish), rough, and hard as the surface is somewhat abrasion resistant after the growth. We postulate that growth of diamond on glassy carbon involves: (i) initial hydrogenation of the graphite edge plane sites forming a diamondlike surface, (ii) nucleation of diamond microparticles on the hydrogenated edge plane sites, and (iii) coalescence of the microparticles into a continuous film. The poor adhesion of diamond to the glassy carbon surface, as grown using our conditions, may result from a combination of growth condition and surface microstructural effects. Results from the characterization of a freestanding film by scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry are presented.