SURFACE PROCESSES AND PHASE-DIAGRAMS IN MBE GROWTH OF SI GE HETEROSTRUCTURE/

The recent results of development and application of MBE methods for d irect growth (self-organization or spontaneous formation) of the heter ostructures GexSi1-x/Si are discussed. The heterostructures involve na noobjects confined in two-or three-dimensional quantum-sized boxes or wires. The influence of substrate temperature, film composition and th ickness on the structure and the surface morphology of the growing fil m were studied. Particular attention was paid to the surface structure evolution of GexSi1-x heteroepitaxial films growing on Si(111)7 X 7 a nd Si(001)2 X 1 substrates over a wide range of concentrations x and g rowth temperatures. The quantum-sized islands can be self-organized af ter achievement of the critical thickness of the pseudomorphic layer; the critical thickness can be calculated in terms of the Frank-van der Merwe theory (when the Stranski-Krastanov growth mechanism is achieve d). It was shown that with respect to the electronic properties, such films demonstrate the behavior of quantum boxes in which a zero-dimens ional electron (hole) gas is localized. A number of heteroepitaxial st ructures with Ge quantum boxes in a tunnel-thin Si layers are grown by MBE and investigated. (C) 1997 Elsevier Science B.V.