Nucleation behaviour of diamond particles on silicon substrates in a hot-filament chemical vapour deposition

Diamond films and particles have been deposited on a silicon substrate using a hot-filament chemical vapour deposition (CVD) method in order to study the effect of hydrogen on the behaviour of diamond nucleation. The nucleation density of diamond was affected by both hydrogen treatment prior to deposition and filament temperature,T_f. The nucleation density was decreased markedly with increasing hydrogen-treatment time. The nucleation density also changed with increasingT_f, which increased initially and then reached a maximum at 2100°C and decreased thereafter. Etching of the substrate surface was observed and enhanced with both increasing hydrogen-treatment time and increasingT_f. The changes in nucleation behaviour were related closely to the etching of substrate surface. These results are explained in terms of the etching of nucleation sites.