研究目的
To realize and characterize mesoscopic Josephson junctions based on InSb nanosheets, investigating supercurrent modulation and multiple Andreev reflections for potential applications in quantum devices.
研究成果
The study successfully fabricated InSb nanosheet-based Josephson junctions with tunable supercurrent and observed high-order multiple Andreev reflections, indicating transparent interfaces. Nb electrodes enable higher temperature and magnetic field operation for future studies.
研究不足
The use of Al electrodes limits measurements to temperatures below 1.1 K and magnetic fields below 100 mT. The switching current may not accurately represent the true critical current due to external circuit effects. Some MAR peaks (e.g., n=3 and 5) are missing without clear explanation.
1：Experimental Design and Method Selection:
The study involves fabricating Josephson junctions using InSb nanosheets grown by molecular-beam epitaxy, with superconducting electrodes (Al or Nb) to induce proximity superconductivity. Methods include electron beam lithography, deposition, and transport measurements in a dilution refrigerator.
2：Sample Selection and Data Sources:
InSb nanosheets were grown on p-type Si substrates using Ag catalysts, with thickness ranging from 10 to 80 nm. Devices were fabricated and measured at cryogenic temperatures.
3：List of Experimental Equipment and Materials:
Equipment includes a molecular-beam epitaxy system, electron beam lithography tools, electron beam evaporator, sputtering system, dilution refrigerator, SEM, and measurement setups with filters for noise reduction. Materials include InSb nanosheets, Ti, Au, Al, Nb, SiO2, and Si substrates.
4：Experimental Procedures and Operational Workflow:
Nanosheets were transferred to substrates, electrodes were patterned and deposited after surface etching, and devices were cooled to 10 mK for four-terminal DC/AC measurements with gate voltage control.
5：Data Analysis Methods:
Data analysis involved measuring current-voltage characteristics, differential conductance, and fitting MAR peak positions to estimate superconducting gaps and other parameters.
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