A DFT study on the surface reaction mechanisms on 4H-SiC surfaces with gaseous species from the MTS-H2 gas-phase system

Abstract

In this work, the investigation focused on the reaction mechanisms of gaseous species in the MTS-H₂ gas-phase system reacting with active surface sites or surface species on 4H-SiC surfaces with the employment of quantum mechanics and density functional theory (DFT). The research was conducted through the application of cluster models which are composed of unreconstructed 4H-SiC bilayers. The applied surfaces in this study include both (0001) face and (000) face, which represent the Si face and C face, respectively. This study reports a total of 32 surface reactions on the (0001) face of 4H-SiC, including 26 reactions with a well-defined transition state and 6 reactions without an obvious transition state, and a total of 34 surface reactions on the (000) face, including 28 reactions with a distinct transition state and 6 reactions without an obvious transition state. This study reports the activation energies of Gibbs free energy and reaction constants of the reactions over the temperature range of 1000 to 1800 K. We investigated the adsorption and reaction activity of several typical gaseous species in the MTS-H₂ gas-phase system on the 4H-SiC surfaces. The reaction paths are discussed, and the reaction constants reported in this work are expected to be employed in the surface kinetics for CVD simulations.