Bjergfelt Martin Saurbrey, Carrad Damon J, Kanne Thomas, Johnson Erik, Fiordaliso Elisabetta M, Jespersen Thomas Sand, Nygård Jesper
Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark.
Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kongens Lyngby Denmark.
Nano Lett. 2021 Dec 8;21(23):9875-9881. doi: 10.1021/acs.nanolett.1c02487. Epub 2021 Nov 22.
We report synthesis of crystalline indium islands on InAs nanowires grown by molecular beam epitaxy. Structural analysis by transmission electron microscopy showed that In crystals grew in a tetragonal body-centered crystal structure within two families of orientations relative to wurtzite InAs. The crystalline islands had lengths < 500 nm and low-energy surfaces, suggesting that growth was driven mainly by surface energy minimization. Electrical transport through In/InAs devices exhibited Cooper pair charging, evidencing charge parity preservation and a pristine In/InAs interface, with an induced superconducting gap ∼ 0.45 meV. Cooper pair charging persisted to temperatures > 1.2 K and magnetic fields ∼ 0.7 T, demonstrating that In/InAs hybrids belong to an expanding class of semiconductor/superconductor hybrids operating over a wider parameter space than state-of-the-art Al-based hybrids. Engineering crystal morphology while isolating single islands using shadow epitaxy provides an interesting alternative to previous semiconductor/superconductor hybrid morphologies and device geometries.
我们报道了通过分子束外延生长在砷化铟纳米线上合成晶体铟岛的过程。通过透射电子显微镜进行的结构分析表明，铟晶体在相对于纤锌矿型砷化铟的两个取向族内以体心四方晶体结构生长。晶体岛的长度小于500纳米且具有低能表面，这表明生长主要由表面能最小化驱动。通过铟/砷化铟器件的电输运表现出库珀对充电现象，证明了电荷宇称守恒以及原始的铟/砷化铟界面，诱导超导能隙约为0.45毫电子伏特。库珀对充电现象持续到温度大于1.2开尔文和磁场约为0.7特斯拉，这表明铟/砷化铟混合体属于一类不断扩展的半导体/超导体混合体，其在比现有基于铝的混合体更宽的参数空间内运行。利用阴影外延在分离单个岛的同时工程化晶体形态，为先前的半导体/超导体混合体形态和器件几何结构提供了一种有趣的替代方案。
