Initial results on the mechanism of carbonization of {001} Si-substrate at high temperature

Abstract In this research, the chemical vapor deposition (CVD) process involving the carbonization of {001} silicon surfaces at a temperature of 1423 K was simulated using quantum metadynamics. The complete sequence of reactions was elucidated, encompassing the creation of an initial SiC crystalline nucleus containing three carbon atoms, occurring alongside native oxide. The analysis of this mechanism encompassed identifying intermediate products and transition states (TS). The overall free energy landscape of the reaction sequence was determined. Carbonization commences with the formation of alkylated surface products and proceeds with hydrogen elimination. Carbon becomes incorporated into the crystal structure only after all covalent interactions with hydrogen are severed. Notably, the presence of native oxide does not hinder the carbonization process. Oxygen atoms exhibit a degree of surface mobility at elevated temperatures. It was observed that hypervalency of carbon is feasible within the transition states. The rate-limiting step in the CVD synthesis of SiC was identified to have an activation-free energy of 166 kj/mol.