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PhD. Topics

Institute of Electrical Engineering SAS

Optimization of the TMD- graphene heterostructures fabrication
PhD. program
Physical Engineering
Year of admission
Name of the supervisor
Mgr. Michaela Sojková, PhD.
Receiving school
Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava
Unlike metallic graphene, some two-dimensional transition metal dichalcogenides (TMD) exhibit semiconductor properties, offering interesting applications in many areas (electronics, sensing). However, for the application of TMD materials, the limiting factor is the small crystallinity of the layers and rapid chemical degradation due to the external environment. One solution to the degradation problem is the use of a protective layer formed by a material that is perfectly insulating (e.g., graphene, h-BN). In the dissertation, we propose a solution based on the simple idea of producing TMD material under graphene. Such a two-dimensional heterostructure will be prepared in one step, where a thin metal layer is covered with a layer of graphene oxide and subsequently annealed in the presence of a chalcogen. During annealing, a TMD layer is formed, while graphene oxide is reduced to graphene. Graphene will serve as a protective layer and prevent oxidation/degradation of the TMD material. This may allow the production of otherwise unstable TMD materials such as NbSe2 or TaS2. We will study how the graphene layer on the metal surface affects the crystallinity and spatial orientation of the final TMD layers. Moreover, these heterostructures in combination with a suitable insulating bottom layer (SiO2, h-BN) may be suitable for multiple applications. The work will focus on optimizing the preparation of TMD-graphene heterostructures using ultrathin layers of various types of 2D TMD materials (PtSe2, MoS2, NbSe2, TaS2). We will investigate the influence of heterostructure preparation parameters on their properties. Prepared heterostructures will be examined using X-ray diffraction analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, optical measurements, electrical property measurements, and other analyses.
The work will be carried out at the Institute of Electrical Engineering SAS, which has the necessary technological and characterization equipment. The PhD student will acquire universal skills with a variety of experimental methods and will be actively involved in several projects.