A MULTIPLE CROSS-SLIP MECHANISM FOR THE GENERATION OF MISFIT DISLOCATIONS IN (001) SEMICONDUCTOR HETEROSTRUCTURES

Misfit dislocations in Cd1-xMnxTe/CdTe(001) epitaxial structures with low mismatch (0-3%) are compared for cases where the deposit is in ten sion and in compression. Where the deposit was in tension, misfit disl ocations were parallel to interfacial [110] directions and were either 60-degrees dislocations with 1/2[110] Burgers vectors inclined to the interface or were 90-degrees dislocations with 1/6[112] Burgers vecto rs bounding intrinsic stacking faults. When the deposit was in compres sion, misfit dislocations had 1/2[110] Burgers vectors inclined to the interface but lay predominantly in [100] directions. These observatio ns are explained by a model where the forces acting on the individual Shockley partials of a dissociated 1/2[110] dislocation tend to widen and narrow the stacking fault for the tension and compression cases re spectively. It is argued that the tendency of the dislocation to becom e undissociated when the deposit is in compression allows alternative slip planes to operate and that [100] segments of dislocation are gene rated by a multiple cross-slip mechanism rather than {110} glide, as p reviously suggested by Bonar, Hull, Walker and Malik. Evidence for the operation of the multiple cross-slip mechanism in a ZnTe/Cd1-xMnxTe s tructure with a high mismatch (5.6%) is also presented and the results compared with those for the lower-mismatch structures.