NUCLEATION AND GROWTH DURING THE CHEMICAL-VAPOR-DEPOSITION OF DIAMONDON SIO2 SUBSTRATES

The early stages of microwave-plasma assisted CVD of diamond on fused silica and silicon substrates were investigated. Nucleation densities on fused silica were somewhat lower than on silicon; however, the diam ond growth rates on fused silica were faster. These results suggest th at the substrate alters the plasma chemistry near the substrate. Trans mission electron microscopy showed a relatively smooth interface betwe en the diamond grains and the SiO2 surface. At low nucleation densitie s, the growth kinetics on both substrates were linear (i.e., the avera ge feature size was proportional to the deposition time), which indica tes that the growth kinetics were initially controlled by reaction(s) at the growing diamond surfaces. The transition to nonlinear growth ki netics observed at higher nucleation densities was probably caused by mass-transport limits.