Adsorption of hydrogen fluoride on SiC surfaces: A density functional theory study

We have carried out first-principles reaction path simulations of hydrogen fluoride (HF) adsorption at steps and terraces of 3C-silicon carbide (SiC) (111) surfaces to investigate initial processes in catalyst-referred etching (CARE). CARE is a novel abrasive-free planarization method and has been invented in our group. In SiC CARE, we use platinum as a catalyst and hydrofluoric acid (HF) solution as an etchant. A crystallographically undamaged and smooth SiC surface is obtained after CARE. In this study, we performed first-principles reaction path simulations using the Simulation Tool for Atom Technology (STATE) program package. Our results showed that the adsorption of HF molecules at step edges has lower activation barrier than that at terraces, and that HF adsorption at F-terminated surfaces is easier than that at OH-terminated surfaces.

► We model initial processes in catalyst-referred etching (CARE). ► We investigate the effects of surface geometries and terminating species on reaction barriers. ► Adsorption of a HF molecule at a step edge Si atom is easier and more stable than that at a terrace site. ► Adsorption of a HF molecule on a F-terminated Si atom is easier and more stable than that on a OH-terminated Si atom.