[20a-A31-1~11] 17.3 層状物質

11:00 〜 11:15奨励賞エントリー英語発表

[20a-A31-8] Atomic Layer Etching of the Quantum Spin Hall Insulator WTe₂ Towards the Study of Topological Josephson Junction Devices

〇(P)Michael Daniel Randle¹, Russell Deacon^1,3, Manabu Ohtomo², Masayuki Hosoda², Kenji Watanabe⁴, Takashi Taniguchi⁵, Shota Okazaki⁶, Takao Sasagawa⁶, Kenichi Kawaguchi², Shintaro Sato², Koji Ishbashi^1,3 (1.Advanced Device Laboratory, RIKEN, 2.Fujitsu Research, Fujitsu Ltd., 3.RIKEN Center for Emergent Matter Science (CEMS), 4.Research Center for Electronic and Optical Materials, NIMS, 5.Research Center for Materials Nanoarchitectonics, NIMS, 6.Laboratory for Materials and Structures, TIT)

キーワード：

Tungsten Ditelluride、Atomic Layer Etching、Josephson Junction

The 2-dimensional (2D), van der Waals materials have a variety of unique optical and electronic properties that have been exploited to create novel Field-Effect Transistors (FETs) and photodetectors. Weak interlayer interactions allow these materials to be isolated in the few- and monolayer limit, a state in which their properties differ significantly from the bulk. We report on an Atomic Layer Etching (ALE) method for WTe₂, a 2D material that undergoes a structural phase transition in the monolayer limit and becomes a Quantum Spin Hall Insulator (QSHI). Given the extreme air sensitivity of this material and its propensity to exfoliate into small monolayers (< 5um), the optimization of an ALE method is critical for creating devices which exploit QSHI physics. Of particular interest are Josephson Junctions, in which a monolayer of WTe₂ is sandwiched between s-wave superconductors. This realizes a proposed geometry for studying Majorana bound states, having applications in fault-tolerant quantum computing. We report on the applicability of our ALE method for etching large, bulk flakes into the few-layer limit as well as for making thin constrictions, which is critical for designing a Josephson Junction device.