Ab initio study of the mechanism of carbonization of {111} Si-substrate at high temperature
In this study, the CVD process of carbonization of {111} silicone surface is simulated employing ab initio metadynamics at the temperature of 1423 K. The entire chain of reactions is discovered, including the formation of an initial SiC crystallite seed with three carbon atoms, in the presence of na...
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Veröffentlicht in: | Materials chemistry and physics 2024-04, Vol.317, p.129180, Article 129180 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | In this study, the CVD process of carbonization of {111} silicone surface is simulated employing ab initio metadynamics at the temperature of 1423 K. The entire chain of reactions is discovered, including the formation of an initial SiC crystallite seed with three carbon atoms, in the presence of native oxide. The characterization of all mechanisms includes transition states (TSs) and intermediate products. The forward free energy barriers were measured when possible. Carbonization always begins with alkylated surface products and progresses through loss of hydrogen. Only when all hydrogen atoms are lost, the carbon is accommodated in the crystal volume. Oxygen atoms of the native oxide may stay trapped in the SiC phase or in a buffer Si–C–O phase, forming a glass layer there. The native oxygen expresses certain mobility at the surface of the material. Occasionally TSs with hypervalent carbon and silicon atoms occur. The rate-determining reaction in the CVD synthesis of SiC has a free energy barrier of 173 kJ/mol.
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•SiC growth by carbonization of {111} Si is simulated by ab initio metadynamics.•Reaction pathways even up to the formation of 3-membered SiC seed were studied.•The transition states and intermediate products are characterized.•The carbon is accommodated in the crystal lattice when all H-atoms are lost.•O-atoms may stay trapped in the SiC phase or in a buffer Si–C–O phase. |
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ISSN: | 0254-0584 1879-3312 |
DOI: | 10.1016/j.matchemphys.2024.129180 |