Bulk InAsSb with 0.1 eV bandgap on GaAs

Abstract

We report on the growth of near-minimum bandgap (0.1 eV) bulk InAs0.54Sb0.46 on GaAs with pronounced photoluminescence. Combining strain-mediating techniques effectively manages the ∼10% lattice mismatch. An interfacial misfit (IMF) dislocation array allows a GaAs substrate and a GaSb buffer layer to act as a direct substitute for a conventional GaSb substrate. We further increase the lattice constant with a linearly graded metamorphic buffer layer of AlGaInSb, upon which we grow an AlInSb virtual substrate with the targeted lattice constant of the active InAsSb region. We observe that the graded buffer not only manages the mismatch between GaSb and InAsSb but also reduces the density of residual threading dislocations from the GaSb/GaAs IMF by a factor of ∼10×. Material characterization demonstrates the viability of using the coupled approach of metamorphic, graded buffers and IMF arrays to manage the large lattice mismatch between the substrate and the mixed group V ternary InAsSb.