Nucleation and growth of heteroepitaxial diamond films on silicon

The introduction of the bias pretreatment process for in-situ nucleation of oriented diamond crystallites on silicon was an important step towards heteroepitaxial deposition of single crystalline diamond films. However, the quality of these films is still limited mainly due to a significant orientational spread of the epitaxial grains around the perfect heteroepitaxial orientation. A further improvement of these films requires an extensive description of the film texture immediately after the nucleation, of its development with increasing film thickness, and an improved insight into the mechanism responsible for the nucleation process. In this report our recent and new results on the heteroepitaxial deposition of diamond on Si(001) and Si(111) and the subsequent textural characterization by X-ray pole figure measurements are reviewed. The possibilities and limits for improving the film quality by an appropriate textured growth step are discussed. Furthermore, optical measurements inside tile plasma during the biasing step and nucleation experiments using patterned substrates indicate that the high field strength above the surface and the resulting acceleration of ions play a dominant role in the formation of diamond nuclei.