Berlin 2024 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 2: 2D Materials and their Heterostructures I: hBN, WSe2, MoS2
DS 2.6: Vortrag
Montag, 18. März 2024, 11:00–11:15, A 060
Photo-electrochemical thinning of transition metal dichalcogenides — •Simon Wörle1, Jeremy Robinson2, Franz Gröbmeyer3, Emiliano Cortes3, and Ian Sharp1 — 1Technical University of Munich — 2Naval Research Laboratory, Washington, D.C — 3Ludwig-Maximilians-Universität München
Two-dimensional transition metal dichalcogenides have attracted considerable attention due to their unique optoelectronic, mechanical and catalytic capabilities. For the application of 2D materials in semiconductor devices, the precise control of their properties is crucial, with the layer number being the most fundamental. Here, we demonstrate a top-down approach in aqueous solutions and under illumination to thin MoS2, WS2, MoSe2 and WSe2 layers of various thicknesses down to, in some cases, a self-limiting number of layers. The removal of the upper layers is initiated by laser illumination with wavelengths of 532nm and 785nm. In contrast to laser degradation in air, where the TMD layers heat and sublimate, the thinning procedure in water is electrochemically driven. Photo-excited holes oxidize the surface layers in a self-limiting mechanism. An additional external voltage applied against a defined reference potential allows this thinning process to be further enhanced or prevented. For potentials larger than 0.8V vs Ag/AgCl, the thinning of MoS2 occurs even under white light microscope illumination. The oxidation, starting at the edges or defects and spreading through the whole TMD flakes, can be in-situ monitored. The presented results show an overview of photo-electrochemical thinning of different TMDs under various bias and excitation conditions.
Keywords: transition metal dichalcogenides; 2D materials; photo-oxidation; photo-electrochemistry; thickness control