Misfit dislocations in (001) semiconductor heterostructures grown by epitaxy

The epitaxial growth and the relaxation of lattice mismatched heterostructu res is discussed in terms of misfit dislocations. Two experimental cases ar e studied: (i) a GaSb/GaAs system perfectly relaxed by a misfit dislocation network characterised as a square array of Lomer dislocations. These misfi t dislocations are created by a periodic mechanism resulting from the islan d growth of GaSb on GaAs. They induce a total accommodation of the lattice mismatch. They are the most efficient and natural misfit dislocations of th e (001) interface: (ii) a GaAs/InP system which is also relaxed by a random ly distributed misfit dislocation network. In this case the density of conv entional misfit dislocation at the level of the interface is too low to exp lain the accommodation of the lattice mismatch. In addition to the misfit d islocations, other crystalline defects, such as clouds of point defects, se em to play a role in the relaxation of the misfit stress. (C) 1999 Elsevier Science S.A, All rights reserved.