Roughening and islanding of monolayer Ge coverage on vicinal Si(001) surface

Roughening and islanding of monolayer Ge coverage on vicinal Si(001) surface has been studied using scanning tunneling microscope (STM). For a 3.9° miscut surface, planar buckled-dimer surface is a metastable state limited by a barrier, which can be overcome by a 680°C annealing. After the annealing, the metastable flat surface has been changed to a rough surface of small hills because of step-bunching, and on top of each hill, a 3 dimensional (3D) nanoscale island was observed. The mechanism of this roughening and islanding process have been discussed.