Temperature dependence of the transition from two-dimensional to three-dimensional growth of Ge on (001)Si studied by reflection high-energy electron diffraction

Germanium islands have been grown on Si(001) by solid-source molecular-beam epitaxy at temperatures between 325 and 900 degrees C. The formation of metastable {105} faceted clusters and macroislands was investigated by real-time reflection high-energy electron diffraction. Up to 600 degrees C, the two-dimensional (2D)-three-dimensional (3D) growth transition through the formation of hut clusters appears at a temperature-independent critical thickness, while the coalescence to macroislands is thermally activated. An activation barrier was also found for the 2D-3D growth transition directly to macroislands at growth temperatures above 600 degrees C. The crossing of the two competing transitions at 600 degrees C determines the two growth regimes. (C) 2000 American Institute of Physics. [S0003-6951(00)02936-3].