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 (hBN). We use the via-based tunneling method to study the single-particle density of states of two different two-dimensional (2D) materials, NbSe2 and graphene. In NbSe2 devices, we characterize the barrier strength and interface disorder for barrier thicknesses of 0, 1 and 2 layers of hBN and study the dependence on tunnel-contact area down to (44±14)2 nm2. For 0-layer hBN 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 hBN barrier. This via-based architecture overcomes limitations of other planar tunneling designs and produces high-quality, ultra-clean tunneling structures from a variety of 2D materials.
@article{arxiv.2203.07394,
title = {Tunneling Spectroscopy of Two-Dimensional Materials Based on Via Contacts},
author = {Qingrui Cao and Evan J. Telford and Avishai Benyamini and Ian Kennedy and Amirali Zangiabadi and Kenji Watanabe and Takashi Taniguchi and Cory R. Dean and Benjamin M. Hunt},
journal= {arXiv preprint arXiv:2203.07394},
year = {2022}
}