2D materials – Transition metal dichalcogenide

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Two-dimensional (2D) materials rank among the most intensely studied materials in condensed matter physics today. Their characteristic feature is a layered structure in which atoms within a single layer are covalently (or ionically) bonded while a relatively weak van der Waals force holds adjacent layers together. The most renowned example of a 2D material is graphene—a single layer of carbon atoms arranged in a hexagonal lattice. The discovery of graphene triggered enormous interest in exploring other 2D crystals, notably the transition metal dichalcogenides (TMDC).

Within the TMDC family, there is a broad range of materials (depending on the chosen transition metal and chalcogen) covering the entire spectrum of electronic properties, from insulators through semiconductors to metals. Furthermore, fascinating quantum states—such as superconductivity or charge density waves—have been observed in certain TMDCs. From the standpoint of modern physics, their topological properties are especially intriguing: features like Dirac and Weyl points or surface states can arise in their band structures, leading to “exotic” phenomena such as topological insulators. Moreover, strong spin-orbit coupling in some TMDCs enables observing the spin Hall effect.

At the Institute of Electrical Engineering, we address 2D materials in collaboration with colleagues from the Department of Microelectronics and Sensorics. In recent years, we have refined the methodology for growing thin layers of several TMDCs, most notably MoS2, WS2, and PtSe2, and more recently, we have also been working with tellurides such as MoTe2, WTe2, and PtTe2. Our research aims to elucidate the relationship between synthesis conditions and the resulting physical and structural properties of these thin-layer systems. To achieve this, we employ various analytical techniques, including Raman spectroscopy, X-ray diffraction (including GIWAXS), imaging and scanning methods (SEM, TEM, AFM), and optical spectroscopy. This approach allows us to examine in detail how various synthesis conditions influence the final structure and the unique electronic properties of TMDC layers.

Recent publications: