Coherent and Incoherent Relaxation in III-V Heterostructures

Abstract

AbstractThe relaxation for large lattice mismatch systems such as GaSb/GaAs and GaAs/InP has been studied by numerical analysis of HREM images. The GaSb/GaAs epitaxial system can be obtained with an interface constituted by a perfect square array of Lomer dislocations. GaSb appears to be coherently and homogeneously relaxed. For GaAs/InP grown at 450°C the GaAs layer becomes well relaxed at some distances from the interface by a network of randomly distributed partial and 60° dislocation segments with a limited length. At low temperature, the plastic relaxation appears directly at the growth front when the individual adatoms take a position different from the ideal pseudomorphic one. In this case, the relaxation mechanism is incoherent.