Scanning tunneling microscopy investigation at high temperatures of islands and holes on Si(111)7x7 in real time: evidence for diffusion-limited decay

The annealing behavior of hole- and island-like nanostructures fabricated i n situ in the scanning tunneling microscope on Si(111)7 x 7 has been invest igated in the range from 720 to 830 K. In contrast to previous work, the an alysis reveals diffusion-controlled decay kinetics to be described by a (t( 0) - t)(2/3) law, From the temperature dependence of the diffusion coeffici ent, we obtain an activation energy of(1.49 +/- 0.12) eV which is discussed in terms of a diffusion barrier for the moving adatoms. The comparison of the decay between hole and island structures suggest a missing Ehrlich-Schw oebel barrier for hole filling. (C) 2001 Elsevier Science B.V. All rights r eserved.