Nanoscale Modification Of Amorphous Diamond-Like Carbon Film Surfaces

Abstract

ABSTRACTScanning Tunneling and Atomic Force Microscopy (STM, AFM) of amorphous tetrahedral carbon films (a-tC) film surfaces grown by pulsed laser deposition indicate extreme flatness and uniform electronic properties.1 This is consistent with the observed predominance of sp3 (diamond-like) bonding in these materials.2 Potential applications of a-tC films may be enhanced with the ability to modify their surfaces on the nanoscale. Exploiting the metastable nature of the sp3 hybridized state of carbon, the high flux electron beam from an STM tip was used to modify ˜100 nm regions; processing in air or in vacuum produces similar results. STM and AFM maps of the modified regions indicate stable morphologic and electronic structures consistent with a local transformation to sp2 (graphitic) hybridization. Surface potentiometric mapping of these regions indicates a correlation between electron dose and a lowering of the surface potential. In addition, spatially-resolved electron energy loss spectroscopy of the modified areas performed with a Scanning Auger Microscope shows plasmon energy shifts that confirm an elevated sp2 content in the modified regions.3