Lattice-Relaxation Process of (InAs)m(GaAs)n Strained Short-Period Superlattices Grown on GaAs

We investigated the lattice-relaxation process in the growth of an (InAs)1(GaAs)4 strained short-period superlattice (SSPS) on GaAs(100) substrates by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM). It was found that the lattice relaxation in the (InAs)1(GaAs)4 SSPS proceeded as rapidly as that in the In0.2Ga0.8As alloy layer. The percentage strain relaxation R XRD, as estimated by XRD measurements, agreed with the calculation results based on the elasticity theory. However, the percentage strain relaxation R TEM, as calculated by measurements of misfit dislocations at the heterointerfaces, was much lower than that estimated by the XRD measurements. It is believed that the difference between the values of R XRD and R TEM are attributable to the nonuniform distribution of strain energy along the growth direction.