Model of the bias-enhanced nucleation of diamond on silicon based on atomic force microscopy and x-ray-absorption studies

The bias-enhanced nucleation of diamond on Si during microwave plasma assis ted chemical vapor deposition has been studied by surface sensitive techniq ues like x-ray-absorption near-edge spectroscopy and atomic force microscop y. It has been observed that the nuclei growth starts on top of a graphitic layer, which contains basal planes oriented perpendicular to the surface. The preferential orientation is likely due to the stress produced by ion bo mbardment during the deposition. The surface termination of the oriented pl anes can be associated with active sites in the diamond nucleation process. Formation of SiC at the surface does not seem related to diamond nucleatio n. The nuclei grow mainly at the expense of carbonaceous adsorbates diffusi ng on the surface, in a process competitive with the formation of oriented graphitic material and new diamond nuclei.