Diamond film nucleation and interface characterization

A powerful micro SIMS technique coupled to a computer driven acquisition system has allowed the simultaneous recording of C⁻, MoO⁻, and Si⁻ images of the sample surfaces, or of the transverse cross sections of the Mo-diamond interface. Diamond deposition has been shown to take place on a Mo₂C layer, and the influence on the nucleation process of Si contamination, coming from the quartz tube etched by H atoms, has been investigated. Contamination can in fact occur during the shutdown procedures or during the whole experiment. This last contamination can be avoided by using suitable pressure ranges or gas combinations. Moreover, the deposition time necessary to obtain well-crystallized diamond films and the nucleation density could be optimized by an in situ pretreatment stage. This treatment reduces the delay observed before nucleation (which would correspond to the carbide formation), and increases the carbon activity at the sample surface.