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Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 74: Poster IIIA

HL 74.9: Poster

Thursday, March 19, 2020, 15:00–17:30, P2/2OG

Photoluminescence monitoring during laser-thinning of transition metal dichalcogenides — •Christian Tessarek, Oleg Gridenco, Kathrin Sebald, Stephan Figge, Jürgen Gutowski, and Martin Eickhoff — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, D-28359 Bremen, Germany

Laser-thinning is a promising tool for processing of two-dimensional materials such as transition metal dichalcogenides (TMDCs) [1]. By laser exposure it is possible to reduce the number of layers locally from multi- down to a monolayer. For a precise layer-by-layer etching process, thinning and simultaneous monitoring is required which can be performed by Raman or photoluminescence (PL) spectroscopy.

This study focusses on PL monitoring during laser-thinning of different trilayer TMDCs such as MoS2, WS2 and ReS2. It will be shown that MoS2 and WS2, which are direct bandgap semiconductors for monolayers, can be thinned down layer-by-layer. The spectral position of the indirect bandgap transition clearly indicates the number of layers, changes abruptly from tri- to bilayer and vanishes for a monolayer. Moreover, a strong increase of the direct bandgap emission indicates thinning from a bi- to a monolayer. Limitations of PL monitoring will also be discussed using the example of ReS2, which remains an indirect bandgap semiconductor even for a monolayer.

[1] A. Castellanos-Gomez et al., Nano Letters 12, 3187 (2012).

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