Misfit dislocations in [001] ZnTe/GaAs strained-layer heterostructures were studied by using high-resolution electron microscopy. It was shown that a new type of dissociated misfit dislocation was present which locally relieved the misfit strain. The reason why this type of dislocation had not previously been observed was that the formation of such a dislocation configuration required a localized negative strain. It was deduced that 3 steps were involved in the generation of this type of dissociated misfit dislocation. Firstly, there was the formation of a growing 30º partial misfit dislocation, that was associated with a stacking fault at the interface, under a misfit strain. Secondly, there was an increase in the width of the stacking fault with increases in the ZnTe epilayer. Thirdly, there was the formation of another 30º partial dislocation at the upper end of the stacking fault; provided that the sign of the local strain became opposite to the original misfit strain due to the excessive growth of misfit dislocations generated in the interface.

P.D.Han, J.Zou: Applied Physics Letters, 1998, 72[19], 2424-6