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)c2×8 surface, at temperatures in the range 150–350 °C. The disorder occurs by the diffusion of surface adatoms in the 〈011¯〉 directions. The disordered regions form at domain boundaries, and grow continuously with temperature until the entire surface becomes disordered at 300 °C. We argue that this phase transition is an example of premelting in two dimensions, i.e., ‘‘edge melting.’’