Cao Qingrui, Telford Evan J, Benyamini Avishai, Kennedy Ian, Zangiabadi Amirali, Watanabe Kenji, Taniguchi Takashi, Dean Cory R, Hunt Benjamin M
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States.
Department of Physics, Columbia University, New York, New York10027, United States.
Nano Lett. 2022 Nov 23;22(22):8941-8948. doi: 10.1021/acs.nanolett.2c03081. Epub 2022 Nov 10.
We introduce a novel planar tunneling architecture for van der Waals heterostructures based on via contacts, namely, metallic contacts embedded into through-holes in hexagonal boron nitride (BN). We use the via-based tunneling method to study the single-particle density of states of two different two-dimensional (2D) materials, NbSe and graphene. In NbSe devices, we characterize the barrier strength and interface disorder for barrier thicknesses of 0, 1, and 2 layers of BN and study the dependence on the tunnel-contact area down to (44 ± 14) nm. For 0-layer BN devices, we demonstrate a crossover from diffusive to point contacts in the small-contact-area limit. In graphene, we show that reducing the tunnel barrier thickness and area can suppress effects due to phonon-assisted tunneling and defects in the BN barrier. This via-based architecture overcomes limitations of other planar tunneling designs and produces high-quality, ultraclean tunneling structures from a variety of 2D materials.
我们基于通孔接触引入了一种用于范德华异质结构的新型平面隧穿架构，即嵌入六方氮化硼（BN）通孔中的金属接触。我们使用基于通孔的隧穿方法来研究两种不同二维（2D）材料NbSe₂和石墨烯的单粒子态密度。在NbSe₂器件中，我们表征了0、1和2层BN势垒厚度的势垒强度和界面无序，并研究了对低至(44 ± 14) nm的隧道接触面积的依赖性。对于0层BN器件，我们展示了在小接触面积极限下从扩散接触到点接触的转变。在石墨烯中，我们表明减小隧道势垒厚度和面积可以抑制由于声子辅助隧穿和BN势垒中的缺陷所产生的影响。这种基于通孔的架构克服了其他平面隧穿设计的局限性，并由多种二维材料制造出高质量、超清洁的隧穿结构。
