Tunneling Spectroscopy of Two-Dimensional Materials Based on Via Contacts.
basic_science · Level V
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- Record sourced from PubMed, PMID 36356229.
- Also identified by DOI 10.1021/acs.nanolett.2c03081.
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Abstract
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 (<i>h</i>BN). We use the via-based tunneling method to study the single-particle density of states of two different two-dimensional (2D) materials, NbSe<sub>2</sub> and graphene. In NbSe<sub>2</sub> devices, we characterize the barrier strength and interface disorder for barrier thicknesses of 0, 1, and 2 layers of <i>h</i>BN and study the dependence on the tunnel-contact area down to (44 ± 14)<sup>2</sup> nm<sup>2</sup>. For 0-layer <i>h</i>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 <i>h</i>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.