The mechanism of epitaxial Si-Ge/Si heterostructure formation by wet oxidation of amorphous Si-Ge thin films

Epitaxial Si-Ge/Si heterostructures have been formed from amorphous Si0.86Ge0.14, Si0.7Ge0.3, and Si0.56Ge0.44 films which were deposited at a vacuum of 10−7 Torr, followed by a wet oxidation process. The presence of an initial native oxide precluded solid phase epitaxy under standard annealing conditions, but epitaxy could be achieved by the use of wet oxidation. The samples were oxidized for various times at 900 °C and examined in reflected electron diffraction, ellipsometry, and cross-sectional and plan-view transmission electron diffraction. The formation of the epitaxial layer has been examined, and an epitaxial growth model is suggested.