Study on the mechanism of platinum-assisted hydrofluoric acid etching of SiC using density functional theory calculations

Hydrofluoric acid (HF) etching of the SiC surface assisted by Pt as a catalyst is investigated using density functional theory. Etching is initiated by the dissociative adsorption of HF on step-edge Si, forming a five-fold coordinated Si moiety as a metastable state. This is followed by breaking of the Si–C back-bond by a H-transfer process. The gross activation barrier strongly correlates with the stability of the metastable state and is reduced by the formation of Pt–O chemical bonds, leading to an enhancement of the etching reaction.