Ken-ichi Itoh and Osamu Matsumoto
Department of Chemistry, College of Science and Engineering, Aoyama Gakuin University, Tokyo 157-8572
The deposition of diamond from the Ar-H2 plasma jets comprising benzene (C6H6) and benzene derivatives, such as cyclohexane (C6H12) and phenol (C6H5OH), as carbon sources was investigated.
First, the diamond deposition from the Ar-C6H6-H2 plasma jet had been carried out and the results obtained were compared with those in the C6H6-H2 microwave plasma. The deposit from the Ar-C6H6-H2 plasma jet exhibited crystalline habit planes and it was identified as the diamond by means of scanning electron microscope observation, X-ray diffraction method, and Raman spectroscopy. However, the diamond deposited from the C6H6-H2 microwave plasma was covered with amorphous components according to scanning electron micrograph, though the diamond was identified in the deposit by means of X-ray diffraction method. Emission band due to C6H6 was observed in the emission spectrum from the C6H6-H2 microwave plasma, but it was not observed in the spectrum from the Ar-C6H6-H2 plasma jet. The dissociation of C6H6 would be promoted in the plasma jet and the diamond could be deposited from the Ar-C6H6-H2 plasma jet.
Second, the diamond was deposited from the Ar-C6H12-H2 plasma jet and the Ar-C6H5OH-H2 plasma jet. The better-faceted and higher-quality diamond was formed from both plasma jets than the deposit from the Ar-C6H6-H2 plasma jet. In the plasma jets, C6H12 and C6H5OH were dissociated and a large amount of H atom and a trace of OH radical were identified. These species prepared in the plasma jets and the adsorbed species on the surface of the deposits would give rise to the deposition of the larger and purer diamond like in the diamond deposition from Ar-chlorinated benzenes-H2 plasma jets.
(Received July 15, 1998; In Final Form September 22, 1998)
diamond deposition, plasma jet, microwave plasma, benzene, benzene derivatives, optical emission spectroscopy
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