Structural and electronic properties of the Si-rich 6H-SiC(0001) surface

Abstract

We have investigated structural and electronic properties of the Si-rich 6H-SiC(0 0 0 1)-3 x 3 surface and the clean root3 x root3R30degrees surface with high resolution electron-energy-loss spectroscopy. We find that the 3 x 3 and the root3 x root3R30degrees surfaces prepared at 980 degreesC are 2D Mott-Hubbard insulators primarily by evaluating the effective on-site Coulomb repulsion energy (U*) energy directly from our electron-energy-loss spectroscopy data. We find that a criterion of U* much greater than t* (t*: intersite hopping energy) is well satisfied for these surfaces thus confirming the typical nature of a Mott-Hubbard insulator. (C) 2002 Elsevier Science B.V. All rights reserved.