Graphene-assisting photo-electrochemical etching of 4H-SiC

Abstract

With the assistance of in-situ grown graphene on the wafers, semi-insulating 4H-SiC wafers were etched in aqueous KOH using photo-electrochemical method. The etching rate was estimated to be at about 50nm/min. By the cross-sectional scanning electron microscope (SEM) images, triangular structure in a similar size and aligned in the same direction was found on (1–100) face. Whereas on the (11–20) faces, pore channels along with [0001] direction exhibitedat the same time. Furthermore, the structure of 4H-SiC and epitaxial graphene on 4H-SiC (0001) face were respectively constructed with the purpose of figuring out the influence of graphene on the process of SiC etching. The electronic structures and electron density were calculated by first principle theory. When SiC was covered by graphene on the top, the intrinsic indirect wide band gap disappeared, though taking over by the single layer graphene characteristic Dirac cone at the Gama point and the linear dispersion representing buffer layer. In addition, predominately contribution at valence band maximum (VBM) and conduction band minimum (CBM) also changed by comparing the distribution of density of state (DOS).