Capturing 3D atomic defects and phonon localization at the 2D heterostructure interface

TL;DR

This study achieves atomic-scale 3D imaging of heterostructure interfaces, revealing defects and localized phonon modes, thereby advancing understanding of structure-property relationships in 2D material interfaces.

Contribution

It introduces a method for direct 3D atomic structure determination at heterostructure interfaces and links atomic defects to vibrational properties.

Findings

Identification of atomic defects and strain at the interface

Observation of localized phonon modes

Correlation of defects with vibrational properties

Abstract

The 3D local atomic structures and crystal defects at the interfaces of heterostructures control their electronic, magnetic, optical, catalytic and topological quantum properties, but have thus far eluded any direct experimental determination. Here we determine the 3D local atomic positions at the interface of a MoS2-WSe2 heterojunction with picometer precision and correlate 3D atomic defects with localized vibrational properties at the epitaxial interface. We observe point defects, bond distortion, atomic-scale ripples and measure the full 3D strain tensor at the heterointerface. By using the experimental 3D atomic coordinates as direct input to first principles calculations, we reveal new phonon modes localized at the interface, which are corroborated by spatially resolved electron energy-loss spectroscopy. We expect that this work will open the door to correlate structure-property relationships of a wide range of heterostructure interfaces at the single-atom level.