Nanoscale Tunnel Junctions and Metallic Single-Electron Transistors via Shadow Evaporation and In Situ Atomic Layer Deposition of Tunnel Barriers
Nanoscale Tunnel Junctions and Metallic Single-Electron Transistors via Shadow Evaporation and In Situ Atomic Layer Deposition of Tunnel Barriers
复制标题
通过隧道势垒的阴影蒸发和原位原子层沉积实现纳米级隧道结和金属单电子晶体管
DOI：
10.1021/acsanm.0c02937
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发表时间：
2021
影响因子：
5.9
通讯作者：
Hirose Fumihiko
中科院分区：
文献类型：
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作者：
Shimada Hiroshi;Koike Takehiro;Kikkawa Keisuke;Konno Hiroki;Ito Naoki;Kobayashi Ryusuke;Mizugaki Yoshinao;Kanomata Kensaku;Miura Masanori;Hirose Fumihiko
纳米尺度金属隧道结是包括超导量子比特、单电子学、纳米自旋电子学和热电子学在内的最新技术的重要组成部分。最广泛使用的通用方法，他们的制造是阴影蒸发通过双层抗蚀剂掩模图案使用电子束光刻。然而，在这种方法中，用于结的电极的可用材料到目前为止是有限的，因为在工艺期间难以在其上形成高质量的隧道势垒。在这项工作中，我们已经开发出一种用于制造纳米隧道结的工艺，其中阴影蒸发方法与原子层沉积（ALD）生长的Al 2 O3隧道势垒原位形成相结合。为了实现这一过程，我们构建了一个真空蒸发器，其中样品室配备了室温远程等离子体ALD装置。该方法能够以0.1纳米量级的精度控制隧道势垒的厚度。我们成功地制作了纳米Ni/Al隧道结和Ni/Al/Ni单电子晶体管，都具有Ni底电极，以及纳米级V/V双超导隧道结使用开发的过程。该工艺扩展了阴影蒸发技术在用于底部电极的各种金属中制造纳米级隧道结的适用性，具有良好质量的隧道势垒。作为具体的应用，它将提高自旋电子学中纳米级隧道自旋注入器的可控性，增加热电子器件的设计自由度，并引入在超导量子电路中使用各种超导金属的可能性。
Nanoscale metallic tunnel junctions are important elements of state-of-the-art technologies including superconducting qubits, single electronics, nanospintronics, and caloritronics. The most widely used versatile method of their fabrication is shadow evaporation through bilayer-resist masks patterned using electron-beam lithography. However, useable materials for the electrodes of junctions in this method were limited thus far because of the difficulty in forming good-quality tunnel barriers on them during the process. In this work, we have developed a process for fabricating nanoscale tunnel junctions in which the shadow evaporation method is combined with an atomic-layer-deposition (ALD)-grown Al2O3tunnel barrier formedin situ. To realize this process, we constructed a vacuum evaporator in which the sample chamber is equipped with a room-temperature remote-plasma ALD apparatus. This method enables control of the thickness of the tunnel barrier with the precision of the order of 0.1 nm. We successfully fabricated nanoscale Ni/Al tunnel junctions and a Ni/Al/Ni single-electron transistor, both having Ni bottom electrodes, as well as nanoscale V/V double superconducting tunnel junctions using the developed process. This process extends the applicability of the shadow evaporation technique for fabricating nanoscale tunnel junctions in various metals for bottom electrodes, with tunnel barriers of good quality. As specific applications, it will improve the controllability of nanoscale tunnel spin injectors for spintronics, increase the design freedom of caloritronic devices, and introduce a possibility to use various superconducting metals in superconducting quantum circuits.