We present helium atom micro-diffraction as an ideal technique for characterization of 2D materials due to its ultimate surface sensitivity combined with sub-micron spatial resolution. Thermal energy neutral helium scatters from the valence electron density, 2-3A above the ionic cores of a surface, making the technique ideal for studying 2D materials, where other approaches can struggle due to small interaction cross-sections with few-layer samples. Sub-micron spatial resolution is key development in neutral atom scattering to allow measurements from device-scale samples. We present measurements of monolayer-substrate interactions, thermal expansion coefficients, the electron-phonon coupling constant and vacancy-type defect density on monolayer-MoS2. We also discuss extensions to the presented methods which can be immediately implemented on existing instruments to perform spatial mapping of these material properties.
@article{arxiv.2409.20461,
title = {Helium atom micro-diffraction as a characterisation tool for 2D materials},
author = {Nick von Jeinsen and Aleksandar Radic and Ke Wang and Chenyang Zhao and Vivian Perez and Yiru Zhu and Manish Chhowalla and Andrew Jardine and David Ward and Sam Lambrick},
journal= {arXiv preprint arXiv:2409.20461},
year = {2024}
}