Control over epitaxy and the role of the InAs/Al interface in hybrid two-dimensional electron gas systems

Abstract

In-situ synthesised semiconductor/superconductor hybrid structures became an important material platform in condensed matter physics. Their development enabled a plethora of novel quantum transport experiments with focus on Andreev and Majorana physics. The combination of InAs and Al has become the workhorse material and has been successfully implemented in the form of one-dimensional structures and two-dimensional electron gases. In contrast to the well-developed semiconductor parts of the hybrid materials, the direct effect of the crystal nanotexture of Al films on the electron transport still remains unclear. This is mainly due to the complex epitaxial relation between Al and the semiconductor. We present a study of Al films on shallow InAs two-dimensional electron gas systems grown by molecular beam epitaxy, with focus on control of the Al crystal structure. We identify the dominant grain types present in our Al films and show that the formation of grain boundaries can be significantly reduced by controlled roughening of the epitaxial interface. Finally, we demonstrate that the implemented roughening does not negatively impact either the electron mobility of the two-dimensional electron gas or the basic superconducting properties of the proximitized system.

12 pages, 7 figures and supplementary material

References in corpus (14)

• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Epitaxy of Semiconductor-Superconductor nanowires
• Hard gap in epitaxial semiconductor-superconductor nanowires
• InAs-Al Hybrid Devices Passing the Topological Gap Protocol
• Coherent manipulation of an Andreev spin qubit
• Transparent Semiconductor-Superconductor Interface and Induced Gap in an Epitaxial Heterostructure Josephson Junction
• Anomalous Fraunhofer Interference in Epitaxial Superconductor-Semiconductor Josephson Junctions
• InSbAs two-dimensional electron gases as a platform for topological superconductivity
• Energy gap measurement of nanostructured thin aluminium films for use in single Cooper-pair devices
• Measurements of Phase Dynamics in Planar Josephson Junctions and SQUIDs
• Flip-chip-based microwave spectroscopy of Andreev bound states in a planar Josephson junction
• Mitigating disorder-induced zero-energy states in weakly-coupled semiconductor-superconductor hybrid systems
• Toward durable Al-InSb hybrid heterostructures via epitaxy of 2ML interfacial InAs screening layers
• Disorder Suppression in Topological Semiconductor-Superconductor Junctions

Cited by in corpus (12)

• Phase-engineering the Andreev band structure of a three-terminal Josephson junction
• Flux-Tunable Josephson Diode Effect in a Hybrid Four-Terminal Josephson Junction
• Demonstration of nonlocal Josephson effect in Andreev molecules
• Zeeman and Orbital Driven Phase Transitions in Planar Josephson Junctions
• Spin-degeneracy breaking and parity transitions in three-terminal Josephson junctions
• Subgap transport in superconductor--semiconductor hybrid islands: Weak and strong coupling regimes
• Development of a Nb-based semiconductor-superconductor hybrid platform
• Observation of an Abrupt 3D-2D Morphological Transition in Thin Al Layers Grown by MBE on InGaAs surface
• Exploring the energy spectrum of a four-terminal Josephson junction: Towards topological Andreev band structures
• Voltage-tuned anomalous-metal to metal transition in hybrid Josephson junction arrays
• Epitaxial aluminum layer on antimonide heterostructures for exploring Josephson junction effects
• Impact of Layer Structure and Strain on Morphology and Electronic Properties of InAs Quantum Wells on InP (001)