Dynamics of the Ge(111)c(2 × 8) surface studied by scanning tunneling microscopy

The scanning tunneling microscope (STM) is used to study the disordering of the Ge(111)c(2 × 8) surface, at temperatures in the range 150-350°C. The disorder occurs by the diffusion of surface adatoms in the 〈011〉 directions. Disordered regions form at domain boundaries of the c(2 × 8) structure, and grow in size continuously with temperature until the entire surface becomes disordered at about 300°C. This order-disorder transition is identified as an example of premelting in two dimensions, i.e., edge melting. Analysis of relatively large STM images is used to obtain statistics for this continuous phase transition. © 1993.