Atomic-force-microscopic study of heteroepitaxial diamond nucleation on (100) silicon

To understand the mechanism of heteroepitaxial diamond growth, the early stage of diamond nucleation, generated in a microwave plasma on negatively biased single crystalline (100) silicon substrates, was observed by atomic force nucroscopy (AFM). The results show that flat non-facetted nuclei are initially formed whose size increases with deposition time. Reflection high energy electron diffraction (RHEED) reveals that the nuclei are of crystalline structure in spite of their very small height of about 5 nm. A critical radius of the nuclei rsubc in the order of nanometers seems to exist under conditions applied in this study. The initial nuclei have only a preferential (100) orientation. By a proper control of the nucleation and growth process, however, one can achieve that only the epitaxially generated nuclei reach rsubc and practically only the oriented nuclei grow larger.