Shot noise detection in hBN-based tunnel junctions

TL;DR

This study demonstrates that atomically thin hBN serves as an effective tunnel barrier in Au/hBN/Au devices, with shot noise measurements aligning with theoretical models, enabling advanced tunneling and noise spectroscopy investigations.

Contribution

First demonstration of shot noise measurement in hBN-based tunnel junctions confirming its high quality as a tunnel barrier.

Findings

Shot noise matches theoretical expectations.

Devices exhibit high-quality tunneling with minimal defects.

hBN is suitable for advanced tunneling spectroscopy.

Abstract

High quality Au/hBN/Au tunnel devices are fabricated using transferred atomically thin hexagonal boron nitride as the tunneling barrier. All tunnel junctions show tunneling resistance on the order of several k$\Omega$/$\mu$m$^{2}$. Ohmic I-V curves at small bias with no signs of resonances indicate the sparsity of defects. Tunneling current shot noise is measured in these devices, and the excess shot noise shows consistency with theoretical expectations. These results show that atomically thin hBN is an excellent tunnel barrier, especially for the study of shot noise properties, and this can enable the study of tunneling density of states and shot noise spectroscopy in more complex systems.