STRAIN RELAXATION IN INALSB EPILAYERS GROWN IN INSB SUBSTRATES

We report a structural study of partially relaxed, 0.1-mum-thick, In1-xAlxSb (0.15<x<0.64) layers grown by magnetron sputter epitaxy on (100) InSb substrates. X-ray diffraction has been used to measure the extent of strain relief as a function of the Al composition and the results have been compared to the well studied InGaAs/GaAs system. The experimental criticial layer thickness is at least five times larger than the critical layer thickness predicted by the mechanical equilibrium model. In addition, a linear relationship was found between the percentage of strain relieved and the normalized thickness of the layers, which suggests that the strain relaxation mechanisms are different for the InAlSb/InSb system. Finally, epitaxial tilting and anisotropy in strain relaxation along [011] directions, as usually found in III-V heterostructures, have not been observed in these layers.