EFFECT OF ANNEALING ON A GE THIN-FILM ON A SI(111)7X7 SURFACE - A STUDY USING ARUPS, XPD, AND LEED

To study the changes in structure and morphology of a Ge thin film as a function of annealing temperature, we implemented complementary surf ace analysis techniques such as angle-resolved ultraviolet-photoelectr on spectroscopy, x-ray-photoelectron diffraction (XPD), and low-energy electron diffraction. The Ge thin film (approximate to 15 Angstrom) w as obtained by exposing a Si(111)7X7 surface to catalytically decompos ed germane at room temperature. The amorphous-crystalline transition t emperature was found to be close to 400 degrees C. A 5X5 reconstructio n of the Ge surface occurred for a 500 degrees C annealing temperature and remained stable to 600 degrees C. This 5X5 surface reconstruction appeared to have an effect on the XPD curve recorded along the ($) ov er bar Gamma-($) over bar Mu line in the 1X1 surface Brillouin zone. A 2.5 degrees shift of the peak located near 55 degrees was observed al ong the [($) over bar 12 $$($) over bar 1] azimuthal direction. Anneal ing at 700 degrees C led to the indiffusion of Ge into Si or to Ge isl anding: the 5X5 surface reconstruction turned into a 7X7 surface recon struction.