FORMATION OF INTERFACIAL DISLOCATION NETWORK IN SURFACTANT-MEDIATED GROWTH OF GE ON SI(111) INVESTIGATED BY SPA-LEED .1.

The relief of strain during hetero-epitaxial growth of non-lattice mat ching materials is an important and unavoidable process, which include s the formation of strain relieving defects such as dislocations. Spot profile analysing low energy electron diffraction (SPA-LEED) has been used to observe for the first time the dynamics of the formation of t hose dislocations in situ during the growth process. Using Sb as surfa ctant in the growth of Ge on Si(111) confines all strain relieving def ects into a periodic network of dislocations at the interface. The dis locations at the interface give rise to an elastic deformation of the film up to the surface, which, due to its regularity, is seen as a spo t splitting in LEED. The exact form of the deformation and thus the ar rangement of the dislocations is deduced from the intensity variation of the satellite spots with energy. The data are in excellent agreemen t with elasticity theory. The dislocations of the three sets do not in tersect in one point but form an extended node with a size of 18 angst rom. The first dislocations are generated at a Ge coverage of 8 monola yers, the final dislocation network is completed just after 10 additio nal monolayers of coverage. The network is detectable at the surface u p to 60 monolayer thickness of the film.