Morphological evolution of Ge islands on Au-patterned Si

We present results on the growth of Ge islands into two-dimensional arrays by molecular beam epitaxy on Au-patterned Si. For a square array of Au dots, a two-dimensional square lattice of Ge islands extending over hundreds of microns has been produced. Islands in the patterned region grow between Au dots and have strikingly different shapes than islands on Au-free Si. For example, square base truncated pyramids grow on Si(0 0 1) while rod-shaped islands grow on Si(1 1 0). Characterization of island development on Si(0 0 1) shows three island shape transitions during growth with the final shape converging to that of the super-dome structure. For both Si(0 0 1) and Si(1 1 0) islands initially grow as “lens-like” structures before nucleating steep {1 1 1} side-facets and transforming into truncated pyramids or rods, respectively.