Pressure-Driven Metallicity in Ångström-Thickness 2D Bismuth and Layer-Selective Ohmic Contact to MoS2

IF 9.1 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters Pub Date : 2025-09-25 DOI:10.1021/acs.nanolett.5c03319

Shuhua Wang, Shibo Fang, Qiang Li, Yunliang Yue, Zongmeng Yang, Xiaotian Sun, Jing Lu, Chit Siong Lau, L. K. Ang, Lain-Jong Li, Yee Sin Ang

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Abstract

Recent fabrication of two-dimensional (2D) metallic bismuth (Bi) via van der Waals (vdW) squeezing offers a route to ultrascaling metal into ångström thickness. However, free-standing 2D Bi is typically semiconducting, which contradicts the experimentally observed metallicity in vdW-squeezed 2D Bi. Here we show that this discrepancy originates from the pressure-induced buckled-to-flat structural transition in 2D Bi, changing the electronic structures from semiconducting to semimetallic. Based on the experimentally fabricated MoS₂-Bi-MoS₂ trilayer heterostructure, we demonstrate the concept of layer-selective Ohmic contact in which one MoS₂ layer forms an Ohmic contact to the 2D Bi while the opposite MoS₂ exhibits a Schottky barrier. The Ohmic contact can be switched between the two sandwiching MoS₂ monolayers by reversing an external gate field, thus enabling charge to be spatially injected into different MoS₂ layers. The layer-selective Ohmic contact proposed here represents a layertronic generalization of semimetal/semiconductor contact, paving the way toward layertronic device application.

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压力驱动Ångström-Thickness二维铋的金属丰度和与MoS2的层选择性欧姆接触

最近通过范德华（vdW）挤压技术制备的二维（2D）金属铋（Bi）提供了一种将金属超尺度化到ångström厚度的方法。然而，独立的二维铋是典型的半导体，这与实验观察到的vdw压缩二维铋的金属丰度相矛盾。在这里，我们表明这种差异源于压力诱导的二维Bi中的屈曲到平坦的结构转变，将电子结构从半导体变为半金属。基于实验制备的MoS2-Bi-MoS2三层异质结构，我们展示了层选择欧姆接触的概念，其中一个MoS2层与二维Bi形成欧姆接触，而另一个MoS2层则表现出肖特基势垒。通过反转外部栅极场，可以在两个夹心MoS2单层之间切换欧姆接触，从而使电荷在空间上注入到不同的MoS2层中。本文提出的层选择欧姆接触代表了半金属/半导体接触的层电子推广，为层电子器件的应用铺平了道路。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nano Letters 工程技术-材料科学：综合

CiteScore

16.80

自引率

2.80%

发文量

1182

审稿时长

1.4 months

期刊介绍： Nano Letters serves as a dynamic platform for promptly disseminating original results in fundamental, applied, and emerging research across all facets of nanoscience and nanotechnology. A pivotal criterion for inclusion within Nano Letters is the convergence of at least two different areas or disciplines, ensuring a rich interdisciplinary scope. The journal is dedicated to fostering exploration in diverse areas, including: - Experimental and theoretical findings on physical, chemical, and biological phenomena at the nanoscale - Synthesis, characterization, and processing of organic, inorganic, polymer, and hybrid nanomaterials through physical, chemical, and biological methodologies - Modeling and simulation of synthetic, assembly, and interaction processes - Realization of integrated nanostructures and nano-engineered devices exhibiting advanced performance - Applications of nanoscale materials in living and environmental systems Nano Letters is committed to advancing and showcasing groundbreaking research that intersects various domains, fostering innovation and collaboration in the ever-evolving field of nanoscience and nanotechnology.