Epitaxial growth of ultrahigh density [Ge.sub.1-x][Sn.sub.x] quantum dots on Si(111) substrates by codeposition of Ge and Sn on ultrathin Si[O.sub.2] films

A method is developed to form epitaxial [Ge.sub.1-x][Sn.sub.x] quantum dots (QDs) on Si(111) substrates by codeposition of Ge and Sn on ultrathin Si[O.sub.2] films with predeposited Ge nuclei. High-resolution transmission electron microscopy has shown that the main formed [Ge.sub.1-x][Sn.sub.x] QDs have less strain and no misfit dislocations.