Interface states in abrupt SiO_2/4H- and 6H-SiC(0001) from first-principles: Effects of Si dangling bonds, C dangling bonds and C clusters

摘要

First-principles calculations of abrupt SiO_2/4H-SiC and 6H-SiC(0001) interfaces have been performed. The calculated interface states, which originate from dangling bonds of interface Si atoms, lie 1.8 eV above the valence band edge of the SiO_2/4H-SiC and the SiO_2/6H-SiC interfaces. These states vanish when Si dangling bonds are saturated with hydrogen atoms. In the carbon cluster model, interface states appear not only at the conduction band edge but also at the valence band edge.