Floating phase in the lattice gas model of Ge(111)

Abstract

Monte Carlo calculations are carried out of the lattice gas model on a triangular net with up to the sixth neighbour interactions, which has been shown previously to reproduce essential features both in the c(2 × 8) and the (1 × 1) state of the (111) surface of Ge. A new phase with characteristics of a floating phase is found to appear in a temperature range between c(2 × 8) and (1 × 1). It is shown that the calculated diffraction peaks which correspond to those from the eighth-order reflections in diffraction experiments are displaced towards the (2 × 2) superlattice Bragg points in the floating phase. The X-ray diffraction experiment on Ge(111) performed by Feidenhans'l et al. is discussed on the basis of the calculations.