Structural Determination of β-SiC(100)- c(2×2) from C-1 s Surface-Core-Exciton and Si- 2p Absorption

Abstract

The marked polarization dependences of two C-1s surface-core-exciton transitions—as revealed by near-edge x-ray absorption fine structure on single-domain $\beta -\mathrm{SiC}\left(100\right)-c(2\times 2)$—are used, together with $\mathrm{Si}-2p$ absorption and molecular orbital cluster calculations, to settle the long-standing controversy over the structure of this surface. The surface is terminated with staggered rows of unusual, nearly triply-bonded C dimers bridging underlayer Si dimers. Resonant valence-band photoemission accompanying $\mathrm{C}-1s$ exciton autoionization reveals directly the electronic structure of the C dimers.