A multiple cross-slip mechanism for the generation of misfit dislocations in (001) semiconductor heterostructures

Publisher Website
Google Scholar
Abstract
Misfit dislocations in Cd1−x MnxTe/CdTe(001) epitaxial structures with low mismatch (0·3%) are compared for cases where the deposit is in tension and in compression. Where the deposit was in tension, misfit dislocations were parallel to interfacial ⟨ 110 ⟩ directions and were either 60° dislocations with ½⟨ 110 ⟩ Burgers vectors inclined to the interface or were 90° dislocations with ⅙⟨ 112 ⟩ Burgers vectors bounding intrinsic stacking faults. When the deposit was in compression, misfit dislocations had ½⟨ 110 ⟩ Burgers vectors inclined to the interface but lay predominantly in ⟨ 100 ⟩ directions. These observations are explained by a model where the forces acting on the individual Shockley partials of a dissociated ½⟨ 110 ⟩ dislocation tend to widen and narrow the stacking fault for the tension and compression cases respectively. It is argued that the tendency of the dislocation to become undissociated when the deposit is in compression allows alternative slip planes to operate and that ⟨ 100 ⟩ segments of dislocation are generated by a multiple cross-slip mechanism rather than {110} glide, as previously suggested by Bonar, Hull, Walker and Malik. Evidence for the operation of the multiple cross-slip mechanism in a ZnTe/Cd1−xMnxTe structure with a high mismatch (5·6%) is also presented and the results compared with those for the lower-mismatch structures.