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arXiv · 2001.05481

Neutral and charged excitons interplay in non-uniformly strain-engineered WS$_2$

Sviatoslav Kovalchuk·Moshe G. Harats·Guillermo López-Polín·Jan N. Kirchhof·Katja Höflich·Kirill I. Bolotin
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Abstract

We investigate the response of excitons in two-dimensional semiconductors subjected to controlled non-uniform strain fields. In our approach to non-uniform strain-engineering, a WS$_2$ monolayer is suspended over a triangular hole. Large ($>2\;\%$), strongly non-uniform ($>0.28\;\%/μm$), and in-situ tunable strain is induced in the monolayer by pressurizing it with inert gas. We observe peak shifts and spectral shape changes in the photoluminescence spectra of strained WS$_2$. We interpret these changes as a signature of increased free electron density and resulting conversion of neutral excitons to trions in the region of high strain. Our result establishes non-uniform strain engineering as a novel and useful experimental `knob' for tuning optoelectronic properties of 2D semiconductors.

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Sviatoslav Kovalchuk, Moshe G. Harats, Guillermo López-Polín, Jan N. Kirchhof, Katja Höflich, Kirill I. Bolotin. 2020-01-15. Neutral and charged excitons interplay in non-uniformly strain-engineered WS$_2$. https://doi.org/10.1088/2053-1583%2Fab8caa

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