| AVS 65th International Symposium & Exhibition | |
| 2D Materials Focus Topic | Monday Sessions |
| Session 2D+MI+NS-MoA |
| Session: | 2D Materials Characterization including Microscopy and Spectroscopy |
| Presenter: | Johannes Jobst, Leiden University, Netherlands |
| Authors: | J. Jobst, Leiden University, Netherlands D. Geelen, Leiden University, Netherlands R.M. Tromp, IBM, T.J. Watson Research Center S.J. van der Molen, Huygens-Kamerlingh Onnes Laboratory, Netherlands |
| Correspondent: | Click to Email |
Knowledge on the interaction between layers is crucial to tailor the properties of van der Waals (vdW) materials. We investigate these using newly developed techniques based on low-energy electron microscopy (LEEM). With LEEM, we probe the reflection of electrons as a function of incoming energy (0-100 eV). We have recently extended our UHV instrument to also measure low-energy electron transmission (eV-TEM).
We apply LEEM and eV-TEM to few-layer graphene. With each layer, an unoccupied interlayer state is added, which hybridizes with the other states. In LEEM, the resulting eigenstates appear as minima in the reflection spectrum. In transmission, they show up as maxima. From both functions, we determine the hybridization energies of the interlayer states, which extend in 2D.
Next, we study the 2D-dispersion relations of these states. For that, we have developed angle-resolved reflected-electron spectroscopy (ARRES) [1]. With ARRES, we investigate few-layer graphene, hBN, as well as their combination. For the latter case we find negligible interaction. [2]
[1] Jobst et al., Nat. Comm. 6, 8926 (2015)
[2] Jobst et al., Nat. Comm. 7, 13621 (2016)