DISSIMILAR GRIT-SIZE DEPENDENCE OF THE DIAMOND NUCLEATION DENSITY ON SUBSTRATE SURFACE PRETREATMENTS

The polycrystalline structure and the physical properties of a diamond film are largely dependent on the number of nuclei per cm2 (nucleation density) which are formed on the substrate surface at the early stage of deposition. We analysed the diamond nucleation density of hot filament chemical vapour deposition (HFCVD) deposits on Si(100) substrate surfaces, as a function of pretreatment and grit size of the abrasive components, keeping constant deposition parameters. In our experiment we pretreated the substrate in two different ways: polishing with a diamond abrasive paste and ultrasonically cleaning in a diamond paste solution. We used scanning electron microscopy (SEM) to measure the diamond nucleation density that may be related to the pretreatments. A different correlation for each pretreatment has been found between the size of the diamond particles present in the pastes and the nucleation density.