抄録
This paper reports a preliminarily study on the formation of diamond on commercially available carbon substrates by means of microwave (2.45 GHz) glow discharge. The features of growri diamond on carbon substrates were compared with that on silicon substrates. Diamond was formed under the following conditions: methane concentration, 0-2.5%; total pressure, 5.3 kPa; substrate temperature, 800-900°C. For identification, the deposits were studied by electron diffraction and Raman spectroscopy. The interlayer spacings of the deposits on carbon substrates are in good agreement with the values reported for diamond. A Raman peak observed at 1333 cm-1 agrees with the reported value of 1332.5 cm-1. The deposits were observed with transmission electron microscopy and scanning electron microscopy. The deposits on carbon substrates are spherical particles without truncation by substrate, which is distinctly different from those on other substrates such as silicon and molybdenum. The shape may be formed by the regression of the substrate surface with the progress of the gasification reaction of substrate with activated hydrogen. The growth features of the deposites on carbon substrates are similar to those on silicon formed under higher methane concentrations. This indicate that the hydrocarbon concentration on a carbon substrate is higher than that on a silicon substrate. Diamond also deposited from only hydrogen gas without methane on silicon substrate set by the side of a carbon substrate. That shows the chemical transport reaction of carbon from carbon substrate to silicon by activated hydrogen.
