Recent developments in heteroepitaxial nucleation and growth of diamond on silicon

After the successful controlled heteroepitaxial nucleation of diamond on SC-SIG epitaxial films and on bare silicon wafers, respectively, obtained by research groups in the USA and Germany in 1992, considerable technical progress and scientifical understanding in the area of heteroepitaxy of CVD diamond have been achieved. The decisive role of ion bombardment for the bias-enhanced epitaxial diamond nucleation is clearly demonstrated. Cross-sectional high resolution electron microscopic (XREM) investigations show the direct epitaxy of diamond on silicon with a periodic 3-to-2 registry of {111} atom planes of the epitaxial diamond-silicon interface. Although the epitaxial growth is of Volmer-Weber type with slight misorientation; i.e., polycrystalline with epitaxial orientation of individual crystallites, the crystallographical and physical properties of these films represent a significant improvement over the usual randomly oriented films, owing to the reduction of the grain boundary angle distribution width to a few degrees. This paper summarizes results obtained recently in our group in the area of heteroepitaxy of diamond on silicon and discusses problems still to be resolved.