Strong substrate strain effects in multilayered WS2 revealed by high-pressure optical measurements

Robert Oliva; Tomasz Woźniak; Paulo E. Faria Junior; Filip Dybała; Jan Kopaczek; Jaroslav Fabian; Paweł Scharoch; Robert Kudrawiec

arXiv · 2202.08551

Strong substrate strain effects in multilayered WS2 revealed by high-pressure optical measurements

Robert Oliva·Tomasz Woźniak·Paulo E. Faria Junior·Filip Dybała·Jan Kopaczek·Jaroslav Fabian·Paweł Scharoch·Robert Kudrawiec

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Abstract

The optical properties of two-dimensional materials can be effectively tuned by strain induced from a deformable substrate. In the present work we combine first-principles calculations based on density functional theory and the effective Bethe-Salpeter equation with high-pressure optical measurements in order to thoroughly describe the effect of strain and dielectric environment onto the electronic band structure and optical properties of a few-layered transition metal dichalcogenide. Our results show that WS2 remains fully adhered to the substrate at least up to a -0.6% in-plane compressive strain for a wide range of substrate materials. We provide a useful model to describe effect of strain on the optical gap energy. The corresponding experimentally-determined out-of-plane and in-plane stress gauge factors for WS2 monolayers are -8 and 24 meV/GPa, respectively. The exceptionally large in-plane gauge factor confirm transition metal dichalcogenides as very promising candidates for flexible functionalities. Finally, we discuss the pressure evolution of an optical transition closely-lying to the A exciton for bulk WS2 as well as the direct-to-indirect transition of the monolayer upon compression.

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Robert Oliva, Tomasz Woźniak, Paulo E. Faria Junior, Filip Dybała, Jan Kopaczek, Jaroslav Fabian, Paweł Scharoch, Robert Kudrawiec. 2022-02-17. Strong substrate strain effects in multilayered WS2 revealed by high-pressure optical measurements. https://arxiv.org/abs/2202.08551

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