Molecular Dynamics Study of Diamond/Silicon (001) Interfaces with and without Graphitic Interface Layers

A theoretical study of diamond/silicon (001) interface structures with and without graphitic interlayers using a density functional based tight–binding molecular dynamics method is presented. The study is motivated by recent progress towards diamond heteroepitaxy on Si (001) using the bias technique. The proposal by Robertson (1995) that an initial graphitic deposit with the graphite planes normal to the Si surface (resulting from carbon subplantation) provides a well matched compliant buffer layer and hence may lower the interface energy is examined. It is found here that the models with “graphitic” or sp bonded interlayers have, in fact, higher energy than those without and that the energy increases with the number of graphitic layers. Residual strain in the graphite planes is found to be one of the reasons for this energetic disadvantage. Si surface dimerization was assumed in the initial structures. email: [email protected]