Epitaxial growth and formation of interfacial misfit array for tensile GaAs on GaSb

The authors report the formation of an interfacial misfit (IMF) array in the growth of relaxed GaAs bulk layers on a (001) GaSb surface. Under specific conditions, the high quality IMF array has a period of 5.6nm and can accommodate the 7.78% tensile GaAs∕GaSb lattice mismatch. The misfit site is identified as a 90° edge dislocation using Burger’s circuit theory and confirmed by high-resolution cross-section transmission electron microscopy (TEM) images. The resulting GaAs bulk material is both strain-free and highly crystalline. Plan-view TEM images show threading dislocation density of ∼3×106∕cm2. This material demonstration will enable novel device structures including an embedded GaSb active region in GaAs device matrix.