Epitaxial Growth Behavior of Ge on Si {111} Surfaces

The morphology of Ge films evaporated on Si {111} surfaces has been investigated by electron diffraction and scanning microscopy. Depending on the cleanness of the substrates, bulk epitaxial Ge or reconstructed Ge growth pyramids with {111} tops and {113}. facets were observed respectively. For clean conditions bulk Ge growth occurs at an epitaxial temperature of 590 degrees C. Formation of reconstructed crystals and an increase of the epitaxial temperature to 870 degrees C is observed under identical experimental conditions during the presence of contaminations. Carbon impurities on the Si substrate resulting evidently from the evaporation source, are believed to be the cause for this latter growth behavior.