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HL: Fachverband Halbleiterphysik

HL 74: Poster IIIA

HL 74.9: Poster

Donnerstag, 19. März 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).