Year: 2026
Type: preprint
Abstract: Electron tunneling is a central transport mechanism in nanoscale devices. The advent of two-dimensional (2D) van der Waals materials has greatly expanded the ability to explore unconventional tunneling phenomena in heterostructures. Conventionally, studies in these systems have focused on tunneling between a pair of electrodes separated by a barrier. Here we report a previously overlooked tunneling pathway in which electrons traverse both the barrier and the electrode to reach semiconductor layers placed outside the junction. We identify this mechanism through the observation of prominent conductance peaks in tunneling transport measurements. Combined transport and optical spectroscopy reveal that the conductance peaks are of different origin than the accompanying electroluminescence. While conductance peaks originate from electrons tunneling through the graphene-hBN-graphene barrier into empty states of the semiconductor, electroluminescence peaks originate from recombination of excitons excited via energy transfer. Our work uncovers the impact of the electronic environment adjacent to tunnel junctions and serves as a pristine probe of the material’s electronic properties. It also establishes a versatile platform for multidimensional investigations of tunneling processes, enabling new designs for on-chip optoelectronic applications.
Source: Research Square
Institutions: ETH Zurich, National Center for Nanoscience and Technology, Empa, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics, Centre National de la Recherche Scientifique, Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, University of Eastern Finland, Institute of Photonic Sciences
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7151226580