The atomic structure of the Si-rich β-SiC(001) 3 x 2 surface reconstruction was solved by grazing-incidence X-ray diffraction with surface and sub-surface structure determination. The reconstruction involves three Si atomic planes (1/3+2/3+1 Si monolayers) in qualitative agreement with ab initio theoretical calculations. The first plane includes Si dimers that were asymmetric with a 0.1Å height difference between Si atoms while the second plane includes Si dimers having alternating long (2.41Å) and short (2.26Å) lengths resulting in long-range influence with no buckling of the top surface dimers, in strong contrast to other group-IV semiconductors. Dimerization was also shown to take place in the third Si plane with a dimer having a bond length at 2.38Å. In addition, a large Si interlayer spacing was found between the reconstructed planes at 1.56Å, significantly larger than that for bulk SiC (1.09Å) and Si (1.35Å) interlayer distances, indicating a very open surface. The results suggest that stress was at the origin of this complex surface organization.

Atomic Structure Determination of the Si-Rich β-SiC(001) 3 x 2 Surface by a Stress-Driven Reconstruction Grazing-Incidence X-Ray Diffraction. M.D’Angelo, H.Enriquez, V.Y.Aristov, P.Soukiassian, G.Renaud, A.Barbier, M.Noblet, S.Chiang, F.Semond: Physical Review B, 2003, 68[16], 165321 (8pp)