Ge-induced surface reconstructions on the 4 degrees vicinal Si(100) surface

We report results of a combined study of low-energy-electron diffraction (L EED) and Monte Carlo simulations for the Ge-adsorbed single-domain stepped Si(100) surface. The (4 x I)structure, least favored energetically among th e (2 x 1) family of the dimer-induced structures, is found to appear on the Ge-adsorbed Si(001) surface in a limited range of temperatures slightly be low room temperature. With mild annealing at similar to 370 K, the surface undergoes irreversible transitions initially to a (3 x 1)and then ultimatel y to a (2 x 1) structure after prolonged annealing. We propose that the (4 x 1) structure consists of an antiferromagnetic arrangement of A-type Ge ad -dimers, which decompose and recombine into C-type ad-dimers for the high-t emperature structures upon annealing. In addition, results of Monte Carlo s imulations suggest that the (4 x 1) surface is the most stable structure wh en the signs of the Ge inter-dimer interaction parameters are exactly oppos ite to those of the c(4 x 2) + p(2 x 1) surface. (C) 1999 Published by Else vier Science Ltd. All rights reserved.