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Effect of reaction pressure on the nucleation behaviour of diamond synthesized by hot-filament chemical vapour deposition

Research paper by Dong -Gook Kim, Hwan -Chul Lee, Jai -Young Lee

Indexed on: 01 Jan '93Published on: 01 Jan '93Published in: Journal of Materials Science



Abstract

Synthetic diamond particles were deposited on a Si (1 0 0) substrate using a hot-filament chemical-vapour-deposition method in order to study the effect of the reaction pressure on the nucleation behaviour. The reaction pressure was controlled, as an experimental variable, from 2 to 50 torr under the following conditions: a filament temperature of 2200 °C, a substrate temperature of 850 °C, a total flow rate of 200 s.c.c.m. and a methane concentration of 0.8 vol%. Diamond deposits on the Si wafer were characterized by micro-Raman spectroscopy, scanning electron microscopy (SEM) and optical microscopy.The maximum nucleation density of diamond particles on the unscratched Si substrate is shown at the reaction pressure of 5 torr. These phenomena can be explained by the competition effect between β-SiC formation, which increases the diamond nucleation density, and atomic-hydrogen etching which decreases the nucleation sites.A new fabrication method for a high-quality diamond film without any surface pretreatments is introduced using a combination process between diamond nucleation at low pressure (5 torr) and growth at high pressure (30 torr).