Characterization of Diamond Film Nucleation and Growth Surface.

摘要

The project has involved advanced studies of diamond nucleation and the diamond growth surface utilizing scanning tunneling microscopy. For diamond growth on Si substrates, diamond nucleation was observed at scratches on the surface. These results were the first reports of nuclei with dimensions less than 100 A. While nucleation was apparently random many nuclei exhibited growth surfaces which paralleled the substrate. Nuclei which exhibited a nearly hemispherical structure were considered to exhibit 3-dimensional type growth. It was found that both flat or 2 dimensional and three dimensional nucleation were observed on the same sample. Scanning tunneling spectroscopy was applied to the nuclei. It was found that the nuclei exhibited characteristics similar to that expected for diamond. In contrast, the substrate showed electronic structure similar to graphite, thus indicating that graphitic layers form on the surface prior to nucleation. The interface of a continuous film was examined by etch removal of the Si, and electronic features characteristic of SiC were observed. A detailed analysis of the STS from diamond surfaces indicated Fowler-Nordheim tunneling. The effect indicated that the valence band minimum was essentially coincident with the vacuum level. The results are consistent with a negative electron affinity for diamond. Diamond surface, Diamond nucleation, Scanning tunneling microscopy.