Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 14: 2D Materials and their Heterostructures II (joint session DS/HL)
HL 14.5: Talk
Tuesday, March 18, 2025, 11:00–11:15, H3
Photo-electrochemical oxidation and thinning of transition metal dichalcogenides — •Simon Wörle1, Lukas Wolz1, Franz Gröbmeyer2, Emiliano Cortes2, Jeremy Robinson3, and Ian Sharp1 — 1Walter Schottky Institute, Physics Department and TUM School of Natural Science, Technical University of Munich — 2Nanoinstitute Munich and Faculty of Physics, Ludwig-Maximilians-Universität — 3Naval Research Laboratory, Washington, D.C
Two-dimensional transition metal dichalcogenides (TMDs) exhibit unique optoelectronic and mechanical properties. For their integration in functional devices and for catalytic applications, it is crucial to understand and control their behavior in the reactive environments. Here, we investigate the stability of thin MoS2, WS2, MoSe2 and WSe2 films in acidic, neutral, and basic solutions using a three-electrode photoelectrochemical cell, which enables experiments under both illumination and in the dark. Under anodic conditions, sulfides and selenides undergo different protonic reactions, depending on the pH of the electrolyte, resulting in different resistances to oxidation. Additional exposure to light from a solar simulator creates photo-excited holes, which drive a self-limiting electrochemical thinning procedure that enables the top-down fabrication of large-area TMDs with a thickness of only a few layers. The degradation, initiated at the edges or defects, propagates through the flakes and can be monitored in-situ using an optical microscope. Under laser excitation, multilayer TMDs can be thinned in predefined patterns, paving a new route for processing and integration of 2D materials into functional devices.
Keywords: transition metal dichalcogenides; 2D materials; oxidation; photo-electrochemistry; thinning