NANOMETER-SCALE GERMANIUM ISLANDS ON SI(111) SURFACE WINDOWS FORMED IN AN ULTRATHIN SILICON DIOXIDE FILM

Three-dimensional Ge islands between 15 and 200 nm in size were found to grow only on Si(111) surface windows in ultrathin SiO2 film after G e deposition and subsequent SiO2 decomposition. The size of Ge islands gradually decreased as the Ge thickness decreased. Pseudomorphic two- dimensional Ge layers with the 5x5 structure formed in surrounding are as of the windows. The windows were produced by selective thermal SiO2 decomposition induced by focused electron beam irradiation. These res ults suggest a new technique for nanometer-scale Ge Island fabrication at given points on Si surfaces. (C) 1998 American Institute of Physic s.