Effect of high supersaturation at the initial stage on diamond nucleation phenomena

Abstract

The surface of diamond film deposited by chemical vapor deposition is usually too rough for it to be used as optical coatings for UV or visible light. The surface roughness is due primarily to the low density of diamond nuclei. To enhance the nucleation density of diamond, we investigated the effect of high supersaturation during an initial stage of deposition on the diamond nucleation phenomena. The deposition process was performed in two sequential steps: first, carbonic material was deposited onto the substrate in a CH 4H 2 plasma for a few minutes; second, diamond particles were grown in a CH 4O 2H 2 plasma for 30 min. The high CH 4 concentration in the initial stage increased the number density of diamond particles by nearly two orders of magnitude. When the high concentration treatment was limited to a few minutes, the deposition of other carbon allotropes was found to be suppressed.