Nucleation and oriented textured growth of diamond films on Si(100) via electron emission in hot filament chemical vapor deposition

Oriented textured diamond films were obtained on Si(100) substrate via electron emission in hot filament chemical vapor deposition (HFCVD). A dc bias voltage relative to the filament was applied to the tungsten electrode between the substrate and the filament. The nucleation and subsequent growth of diamond films were characterized by scanning electron microscopy and Raman spectroscopy. The experimental results showed that the electron emission from the diamond coating on the electrode plays a critical role during the nucleation. The maximum value of nucleation density is up to 1011 cm-2 on pristine Si surface at emission current of 250 mA. The effect of the electron emission on the reactive gas composition was analyzed by in situ infrared absorption, indicating that the concentration of CH3 and C2H2 near the substrate surface is extremely increased. This may be responsible for the enhanced nucleation by electron emission.