Journal
NANO LETTERS
Volume 19, Issue 5, Pages 3083-3090Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b00494
Keywords
Superconductor-semiconductor; epi-Al/InAs; one-dimensional channel; quantum point contact; ballistic Josephson junction; topological superconductor network
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Funding
- Microsoft Research and California NanoSystems Institute in Santa Barbara
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One-dimensional (1D) electronic transport and induced superconductivity in semiconductor nanostructures are crucial ingredients to realize topological superconductivity. Our approach for topological superconductivity employs a two-dimensional electron gas (2DEG) formed by an InAs quantum well, cleanly interfaced with an epitaxial superconductor (epi-Al). This epi-Al/InAs quantum well heterostructure is advantageous for fabricating large-scale nanostructures consisting of multiple Majorana zero modes. Here, we demonstrate transport studies of building-blocks using a high-quality epi-Al/InAs 2DEG heterostructure, which could be put together to realize various proposed 1D nanowire-based nanostructures and 2DEG-based networks that could host multiple Majorana zero modes. The studies include (1) gate-defined quasi-1D channels in the InAs 2DEG and (2) quantum point contacts for tunneling spectroscopy, as well as induced superconductivity in (3) a ballistic Al-InAs 2DEG-Al Josephson junction. From 1D transport, systematic evolution of conductance plateaus in half-integer conductance quanta is observed with Lande g-factor of 17, indicating the strong spin-orbit coupling and high quality of the InAs 2DEG. The improved 2DEG quality leads to ballistic Josephson junctions with enhanced characteristic parameters such as IcRn and IexcRn, the product of superconducting critical current I-c (and excess current I-exc) normal resistance R-n. Our results of electronic transport studies based on the 2D approach suggest that the epitaxial superconductor/2D semiconductor system with improved 2DEG quality is suitable for realizing large-scale nanostructures for quantum computing applications.
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