Electronic contributions to scanning-tunneling-microscopy images of an annealed β-SiC(111) surface

Abstract

The reconstruction of the cubic β-SiC(111) surface was studied after annealing at ∼1200 °C. The surface consistently showed a 6 √3 ×6 √3 geometry when measured by low-energy electron diffraction (LEED) and a 6×6 geometry when imaged by scanning tunneling microscopy (STM). To resolve the discrepancy, we carried out first-principles calculations of the electronic structure of a surface model in which a graphite monolayer was incommensurately grown on top of the Si-terminated β-SiC(111) surface. The calculated energy band and density-of-states diagrams provide an explanation to the observed differences in LEED and STM results. They also explain the voltage-dependent contrast-reversal phenomenon observed in the STM images of the annealed surface.