Surface diffusion and phase transition on the Ge(111) surface studied by scanning tunneling microscopy

Abstract

The formation of disordered regions is observed on the Ga(111)c2\ifmmode\times\else\texttimes\fi{}8 surface, at temperatures in the range 150--350 \ifmmode^\circ\else\textdegree\fi{}C. The disorder occurs by the diffusion of surface adatoms in the 〈011\ifmmode\bar\else\textasciimacron\fi{}〉 directions. The disordered regions form at domain boundaries, and grow continuously with temperature until the entire surface becomes disordered at 300 \ifmmode^\circ\else\textdegree\fi{}C. We argue that this phase transition is an example of premelting in two dimensions, i.e., ``edge melting.''