Nucleation and initial growth of diamond by biased hot filament chemical vapour deposition

The nucleation and initial growth of diamond on Si(100) in biased hot filament chemical vapour deposition have been investigated by atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. For positive bias values of 75 V, the nucleation density was found to be 106 cm^-2 for non-scratched silicon. The maximum value of the nucleation density was over 10¹¹ cm^-2 on mirror-polished Si(100) at -300 V. The transportation process of the ion flux from the filament to the substrate is discussed in detail for biased substrates. The nucleation enhancement by the positive bias is believed to be a result of the increased impingement of the electrons emitted from the filament to the substrate surface. The studies have shown that electron emission from diamond plays a key role in negative-bias-enhanced nucleation by accelerating the dissociation of molecular hydrogen and hydrocarbon species into various free radicals and causing a plasma to be ignited near the substrate surface. The negative bias pretreatment is also a critical step in growing heteroepitaxial diamond films: the enlargement of the area of diamond clusters in contact with the substrate enhances the orientated growth of the films. © Springer-Verlag 1997.