Elemental Dislocation Mechanisms Involved in the Relaxation of Heteroepitaxial Semiconducting Systems

Different elemental dislocation mechanisms are considered and we try to highlight their special behaviour in relation to the layer geometry. The nucleation of misfit dislocations is the first step, we show here that the mechanism proposed by Matthews et al. can actually be observed in low misfit systems. The development of dislocations is then studied and we underline some particular problems which could influence the dislocation length: the role of the cooling step and of the uncertainty on Gdk, the formation energy of kink pairs. The interactions between emerging segments or an emerging segment and a misfit dislocation are reviewed. Finally the role of dislocation cross slipping is discussed and it is shown that in epitaxial stressed films this mechanism is favoured by the shrinkage of the fault ribbon.