PRESSURE EFFECT ON DIAMOND NUCLEATION IN A HOT-FILAMENT CVD SYSTEM

Using extraordinarily low pressure (0.1-1 Torr) we obtained high-densi ty nucleation of diamond on mirror-polished silicon in a hot-filament chemical vapor deposition (HF-CVD) system. A diamond nuclei density as high as 10(10)-10(11) cm(-2) was achieved, which was comparable to th e largest nuclei density obtained in a microwave-plasma chemical vapor deposition system. The low-pressure nucleation technique and the pres sure effect on diamond nucleation were discussed in detail based on mo lecular dynamics. The enhanced nucleation at low pressure was attribut ed to an increased mean free path, which gave rise to an increased con centration of nucleating species at the substrate and other beneficial nucleating factors. The present work suggests that very low pressure may be an effective approach to nucleate and grow diamond films on unt reated substrates via HF-CVD.