FABRICATION OF SNXGE1-X THIN-FILMS WITH NONEQUILIBRIUM COMPOSITION

Amorphous films of Sn/Ge alloy were produced by coevaporation of tin a nd germanium onto substrates held at or below room temperature. A comp ositional gradient was introduced by means of a mask placed at an appr opriate distance from the substrate; transmission electron microscopy and energy-dispersive X-ray analysis were used to determine the local structure and chemical composition. The as-deposited films were amorph ous and single-phase up to 15 at% Sn, or up to 45 at% Sn for substrate s cooled to 100 K during deposition. When heated to 120 degrees C, the films crystallized to a diamond-cubic structure, with some precipitat ion of metallic tin. Copyright (C) 1996 Elsevier Science Ltd