Strain Relaxation Process of (InAs)m(GaAs)n Strained Short-Period Superlattices Grown by Molecular Beam Epitaxy

The strain relaxation process and crystalline quality of (InAs) m (GaAs) n strained short-period superlattices (SSPSs) grown on a GaAs(001) substrate were investigated by transmission electron microscopy and double-crystal X-ray diffraction. The lattice mismatch between the superlattice and the substrate was mainly accommodated by the generation of misfit dislocations propagating parallel to the heterointerface with no threading dislocations. However, the density of misfit dislocations was relatively low in the single SSPS heterostructure. Moreover, the full width at half-maximum of X-ray diffraction was markedly increased with the generation of misfit dislocations. It was found that the residual strain of SSPS was effectively relieved by applying multiple SSPS heterostructures.