Direct observation of synchrotron-radiation-stimulated desorption of thin SiO2 films on Si(111) by scanning tunneling microscopy

This is the first report of the use of scanning tunneling microscopy (STM) to study changes in the surface morphology during synchrotron-radiation (SR ) stimulated desorption of SiO2 films on Si(111). An atomically flat surfac e was obtained after SR irradiation for 2 h at a surface temperature of 700 degrees C. The STM topograph indicates that the SR desorption mechanism is quite different from the thermal desorption of SiO2. The lack of formation of multi-step holes on the exposed silicon surface indicates that the deso rption of oxygen atoms and molecules by SR excitation leaving volatile SiO is an important mechanism. (C) 1999 Elsevier Science B.V. All rights reserv ed.