CPM Seminar

Van der Waals Epitaxy of Transition Metal Disulphide Nanostructures: Tailoring Electronic Structure by Growth Variations

Borna Pielić

Universität Siegen

Semiconducting transition metal dichalcogenides (TMDs) are fascinating due to their exceptional properties at the atomic scale: direct band gap, strong exciton binding energy, high charge mobility, and high thermal conductivity. These properties make two-dimensional (2D) TMDs excellent candidates for applications such as photodetectors, solar cells, light-emitting devices, field-effect transistors, and sensing devices.

When studying the intrinsic properties of 2D materials, it is desirable to grow them on a weakly interacting substrate, most commonly another 2D material. We have epitaxially grown MoS₂ on graphene and investigated the effects of self-intercalation (intercalation of native atoms of the TMD) using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Our findings indicate that the interaction between graphene and MoS₂ is tunable, resulting in lattice strain and dielectric screening, both of which significantly influence the electronic structure, recorded by scanning tunnelling spectroscopy (STS) (1). Additionally, interlayer charge correlations may give rise to plasmonic features in the spectra.

Our research also explores lateral and vertical TMD heterostructures composed of semiconducting MoS₂, WS₂, and metallic TaS₂. Through band bending measurements using STS, we observe atomically sharp pn and Schottky junctions.

[1] Pielić, B., Mužević, M., Novko, D., Jiaqi, C., Bremerich, A., Ohmann, R., Kralj, M., Šrut Rakić, I., Busse C., Probing the interplay of interactions, screening and strain in monolayer MoS₂ via self-intercalation. npj 2D Mater Appl 8 61 (2024).