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| Home > Publications database > Zur Bedeutung des atomaren Wasserstoffs in der Niederdruck Diamantsynthese |
| Book/Report | FZJ-2019-01250 |
1995
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/21549
Report No.: Juel-3154
Abstract: Growth of diamond at low pressures is currently investigated due to its high potential in industrial applications. Usually the chemical vapor deposition (CVD) process is perfonned in a gas mixture of a few percent of hydrocarbons like methane or acetylene, diluted in hydrogen. The gas phase in front of the substrate is activated by a hot filament, by means of a microwave plasma or a glow discharge. In addition to hydrocarbon radicals this activation provides hydrogen atoms which are assumed to support or even enable diamond growth by the following processes: - production of hydrocarbon radicals which supposedly are growth species, - energy transport from the gasphase to the substrate by recombination reactions of atomic hydrogen on the substrate surface, - stabilization of the diamond surface during the growth process by the termination of dangling bonds, activation of the surface by the abstraction of single terminating hydrogen atoms, - etching of codeposited graphitic material on the substrate. The various functions of the atomic hydrogen reveal its fundamental importance in the growth process. These functions have been investigated in the present work. The growth rate of diamond films has been determined for a set of films deposited at different substrate temperatures. From the variation with temperature an overall activation energy of the growth process of 19 kcallmol has been derived. This activation energy has been interpreted as that of the initial growth step which is the surface hydrogen abstraction reaction. Films deposited at the maximum growth rate are those of the highest quality as assessed by raman spectrocopy. However, all the films contain substantial amounts of hydrogen which is inhomogeneously distributed and mostly incorporated at the grain boundaries of the polycrystalline films. [...]
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