Effective fabrication of 2D TMDs with the aid of in-situ microscopy

Two-dimensional (2D) Janus transition metal dichalcogenides (Janus 2D TMD) are specific planar materials with different top and bottom termination layers. This new class of materials thus exhibits broken structural symmetry in the out-of-plane direction, predicted to result in exotic new properties, such as vertical piezoelectricity, Rashba spin splitting and unexpected exciton behavior. However, fabrication of Janus 2D TMD is an extremely challenging task, owing to the need of an epitaxial atomic replacement within classical 2D TMD. This project is designed to achieve chalcogenide exchange within classical TMDs by two novel approaches. In the first approach, we will utilize an electron beam as tool to alter the top layer, allowing its selective selenization/sulfurization. In the second approach, we aim to utilize increased reactivity in the van der Waals gap to allow for selective chalcogenide exchange within the gap. This requires careful set of experimental conditions. These will be sought with in-situ electron microscopy, which allows to overcome the common experimental ""black box"" approach. Data from in-situ microscopy allow to determine kinetic constants, potentially allowing to generate general growth protocols for Janus TMDs. The growth will be followed analysis of structural, optical and electrical properties of the grown materials. The proposal builds on an established know how of the Host institution (CEITEC) and the Supervisor (Miroslav Kolibal), providing the Aplicant (Estácio Paiva de Araújo) with relevant scientific training, as well as widening his skillset via Career Development Plan. The project emphasizes the two-way knowledge transfer