Abstract: The nucleation and growth of diamond film under transverse bias was investigated in a hot-filament
chemical vapor deposition system. It was shown that the nucleation density of diamond is enhanced with the increasing of transverse bias
current. A nucleation density of 1.1×10⁸cm^-2 can be obtained, but transverse bias is harmful to the growth of diamond film. In situ
optical emission spectroscopy technology was used to study the diamond film deposition process. The results showed that the improvement of the
nucleation density and the harm of the growth may be caused by the abundance of atomic hydrogen and CH radical which is favorable to the formation
of thin amorphous carbon layers.

Key words: diamond film, transverse bias, in situ optical emission spectroscopy, amorphous carbon layer