Characterization of laser-irradiated surfaces of a polycrystalline diamond film with an atomic-force microscope

A polycrystalline diamond film was etched down to a depth corresponding to the grain size with 193 nm excimer laser radiation. Below a graphitic surface layer (GL) we have observed a highly stable layer (SL) which is conducting. Atomic force microscope measurements were made in order to characterize the topography and microfriction of these two surface layers. Features of the diamond facet structure are still visible in spite of smoothening by the laser etch process. An approximation for the friction coefficient of both surface layers yields values of between 0.01 and 0.1. The friction pictures of the GL show a local period length of about 70 nm, which could be a typical diameter for micrographitic grains. The SL is more disrupted than the GL and the appearence of a period length of about 70 nm has faded discernibly.