Contribution of top barrier materials to high mobility in near-surface InAs quantum wells grown on GaSb(001)

Abstract

Near-surface InAs two-dimensional electron gas (2DEG) systems have great potential for realizing networks of multiple Majorana zero modes towards a scalable topological quantum computer. Improving mobility in the near-surface 2DEGs is beneficial for stable topological superconducting states as well as for correlation of multiple Majorana zero modes in a complex network. Here, we investigate near-surface InAs 2DEGs (13 nm away from the surface) grown on GaSb(001) substrates, whose lattice constant is closely matched to InAs, by molecular beam epitaxy. The effect of 10-nm-thick top barrier to the mobility is studied by comparing Al${}_{0.9}$Ga${}_{0.1}$Sb and In${}_{0.75}$Ga${}_{0.25}$As as a top barrier on otherwise identical InAs quantum wells grown with identical bottom barrier and buffer layers. A 3-nm-thick capping layer on Al${}_{0.9}$Ga${}_{0.1}$Sb top barrier also affects the 2DEG electronic transport properties by modifying scattering from 2D remote ionized impurities at the surface. The highest transport mobility of 650,000 cm${}^2$/Vs with an electron density of 3.81 $\times$ 10${}^{11}$ cm${}^{-2}$ was observed in an InAs 2DEG with an Al${}_{0.9}$Ga${}_{0.1}$Sb top barrier and an In${}_{0.75}$Ga${}_{0.25}$As capping layer. Analysis of Shubnikov-de Haas oscillations in the high mobility sample suggests that long-range scattering, such as remote ionized impurity scattering, is the dominant scattering mechanism in the InAs 2DEGs grown on GaSb(001) substrates. In comparison to InAs quantum wells grown on lattice-mismatched InP, the ones grown on GaSb show smoother surface morphology and higher quantum mobility. However, In${}_{0.75}$Ga${}_{0.25}$As top barrier in InAs quantum well grown on GaSb limits the transport mobility by charged dislocations formed in it, in addition to the major contribution to scattering from the alloy scattering.

References in corpus (18)

• Spintronics: Fundamentals and applications
• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Helical liquids and Majorana bound states in quantum wires
• Evidence of Majorana fermions in an Al - InAs nanowire topological superconductor
• Scalable Designs for Quasiparticle-Poisoning-Protected Topological Quantum Computation with Majorana Zero Modes
• Quantized Majorana conductance
• Non-Abelian quantum order in spin-orbit-coupled semiconductors: The search for topological Majorana particles in solid state systems
• Two-dimensional epitaxial superconductor-semiconductor heterostructures: A platform for topological superconducting networks
• Two-dimensional platform for networks of Majorana bound states
• Zero-Energy Modes from Coalescing Andreev States in a Two-Dimensional Semiconductor-Superconductor Hybrid Platform
• Quantized conductance doubling and hard gap in a two-dimensional semiconductor-superconductor heterostructure
• Experimental and materials considerations for the topological superconducting state in electron and hole doped semiconductors: searching for non-Abelian Majorana modes in 1D nanowires and 2D heterostructures
• Transport studies of epi-Al/InAs 2DEG systems for required building-blocks in topological superconductor networks
• Scattering mechanisms of highest-mobility InAs/Al${}_x$Ga${}_{1-x}$Sb quantum wells
• High mobility InAs 2DEGs on GaSb substrates: a platform for mesoscopic quantum transport
• Mobility in excess of $10^6$ cm${}^2$/Vs in InAs quantum wells grown on lattice mismatched InP substrates
• On the limits to mobility in InAs quantum wells with nearly lattice-matched barriers

Cited by in corpus (9)

• Gate-tunable Superconducting Diode Effect in a Three-terminal Josephson Device
• Transport Studies in a Gate-Tunable Three-Terminal Josephson Junction
• Transport studies of epi-Al/InAs 2DEG systems for required building-blocks in topological superconductor networks
• Selective Control of Conductance Modes in Multi-terminal Josephson Junctions
• Experimental Measurements of Effective Mass in Near Surface InAs Quantum Wells
• Controlling Fermi level pinning in near-surface InAs quantum wells
• Design of a Josephson diode based on double magnetic impurities
• Field effect two-dimensional electron gases in modulation-doped InSb surface quantum wells
• High transparency induced superconductivity in field effect two-dimensional electron gases in undoped InAs/AlGaSb surface quantum wells