Abstract
The demand for n-type diamond semiconductor with high electron conductivity at room temperature. is increasing. To synthesis high quality n-type diamond by a chemical vapor deposition (CVD), it is important to investigate the reaction of sulfur on diamond surface. In this study, the reaction of H2S on diamond surface in microwave plasma assisted CVD process was investigated. Hydrogen-terminated synthetic diamond powder was placed into the CVD reactor, and then 500 ppm H2S in hydrogen was introduced into the reactor and the reaction was carried out for 1 hour in the temperature range of 573-1073 K. The reacted diamond samples were analyzed by XPS and FT-IR. All sample showed a peak at S2p region, proving the existence of sulfur. The strength of the peak depended on the reaction temperature. The result of quantitative analysis showed that the atomic ratio of reacted sulfur to carbon was largest at 673 K. A series of Diffuse Reflectance Infra-red Fourier Transform (DRIFT) spectra of the reacted samples in the temperature range of 573-973 K, showed peaks related to the sulfur compounds containing C-S bonds. This confirms that sulfur on the diamond surface is chemically bonded to the diamond surface. The shapes of spectra depended on the reaction temperature suggesting that different species are generated on the diamond surface at different temperatures. The species verified on the diamond were C-S-C and C=S. However, no evidence of C-SH group was discovered.
