Energetics of the α-SiC(0001)-(3x3) surface reconstruction

The paper presents an analysis of the energetics of a few possible candidates for the structural model of the (3 x 3) reconstruction of the alpha-SiC(0001) surface. The analysis is based on quantum chemical calculations of the MNDO type (AMI parametrization). The results indicate that of the models tested, the newly proposed model of Starke et al. [Phys. Rev. Lett. 80 (1998) 758] is the only energetically feasible model for the reconstruction. Moreover, Si atoms in this and other structures of lower Si coverage appear to be bonded to the stoichiometric surface more strongly than single Si adatoms in the (root 3 x root 3) pattern. The last result confirms the experimental finding of Tsukamoto et al. [T. Tsukamoto, M. Hirai, M. Kusaka, M. Iwami, T. Ozawa, T. Nagamura, T. Nakata, Surf. Sci. 371 (1997) 316] that Si adatoms are not likely candidates for the structural elements building the (root 3 x root 3) reconstruction. (C) 1998 Elsevier Science B.V. All rights reserved.