Atomic-Level Investigation ofCHxandC2HxAdsorption onβ-SiC (111) Surface for CVD Diamond Growth from DFT Calculations

Abstract

The focus of this paper is on the adsorption of unsaturated hydrocarbon molecules onβ-SiC (111) surfaces during diamond film growth. TheCHxandC2Hxmolecules have been investigated to obtain a specific insight into absorbing diamond processes on the atomic scale. Structural and electronic properties ofCHxandC2Hxadsorption on the Si- and C-terminated surfaces have been studied by first-principles calculations based on density functional theory (DFT). From the calculated energetics and geometries, we find thatC2Hxadsorption on the Si-terminated surfaces has six possible surface reconstructions. For the C-terminated surface, there exist eight possible surface reconstructions. Five surface reconstructions, includingCH2adsorption on the Si- and C-terminated surface, CH–CH2and CH=CH2adsorption on the C-terminated surface, andC2H5adsorption on the Si-terminated surface, have the largest hydrogen adsorption energies and more stability of surface reconstructions. Calculations demonstrate that the Si-terminated surface is energetically more favorable for fabricating CVD diamond coatings than the C-terminated surface.