Scanning tunneling microscopy study of Si(111) surface morphology after removal of SiO2 by synchrotron radiation illumination

The surface morphology of Si(111) was investigated using scanning tunneling microscopy after desorption of surface SiO2 by synchrotron radiation (SR) illumination. The surface shows large regions of atomically flat Si(111)-7x 7 structure, and is characterized by the formation of single bilayer steps nicely registered to the underlying crystal structure. This is in sharp con trast to Si(111) surfaces after thermal desorption of SiO2 at temperatures 880 degrees C and above, where the surface steps are much more irregular. T he registration of the surface steps to the underlying crystal structure in dicates that the Si(111) surface reaches thermodynamic equilibrium under SR irradiation at temperatures much lower than that necessary for thermal des orption. (C) 2000 American Institute of Physics. [S0003-6951(00)00511-8].