Stability and surface properties of Ge-Si alloy films on Si (111) substrate.

Several Ge-Si alloy films with different surface properties were prepared from a 500angstroms thick Ge film that had previously been grown on a Si(111)-7x7 substrate by molecular beam epitaxy. The films were prepared by combinations of sputtering, annealing and Ge deposition from an evaporator. The surface properties were studied by Auger electron spectroscopy (AES) and by low energy electron diffraction (LEED). A novel LEED system employing position sensitive pulse detection was used. The Ge film surface gave a superposition of 7 x 7 and c 2 x 8 LEED patterns.