Optimization of hybridized InAsSb/InGaSb semiconductor topological materials

Abstract

Generating large topologically protected surface currents using conventional III-V infrared materials such as InAsSb/InGaSbAs quantum wells (QWs) and superlattices (SLs) has been important. In such materials, topological states can be formed at the edge by hybridizing ordinary electronic band structures. However, achieving large surface currents out of these materials is still difficult due to low emission currents and high carrier defects. In this work, we present two hybridized topological structures: one for the 6.22 Å metamorphic QWs and the other for the 6.10 Å pseudomorphic SLs. Both structures are tailored for the same hybridization gap (Δ) of ∼60 meV and optimized for the minimum crystal defects. While the QW grown on metamorphic buffers generates a significant amount of mismatch-related crystal defects, the SL grown on lattice-matched buffers produces an excellent crystalline-quality. Quasiparticle interference mapping and calculations on a SL sample show good agreement of the band structure.