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

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. © 1991 The American Physical Society.