Issue 6, 2020

Strain manipulation of the polarized optical response in two-dimensional GaSe layers

Abstract

We report tunable optical performances of gallium selenide (GaSe) layers in phonon vibrations, band edge emission, circular polarization, and anisotropic response via strain manipulation. By applying a uniaxial tensile strain, frequency shift and peak broadening are observed in Raman spectra. A shrink in bandgap is demonstrated in photoluminescence (PL) spectra and confirmed by first-principles calculations. A continuously growing circular polarization from 3.8% to 37.9% is detected at room temperature when the tensile strain is increased from 0% to 0.35%, which is almost a ten-fold enhancement compared with that under the non-resonant excitation. Through the theoretical calculations, the decrease in exciton lifetime is revealed to be responsible for the overwhelming enhanced circular polarization. By deforing the lattices of GaSe layers, the Raman intensity was found to be suppressed in the strain direction. The intrinsic fourfold-symmetry of the E2g1 mode in angle-dependent Raman spectra is tuned to a two-fold symmetry. An anisotropic PL response is further regulated by changing the structural symmetry of GaSe lattices. A maximal polarization of 66.0% is achieved when the detection polarizations are perpendicular to the strain direction. All the findings in this study suggest a route for tuning the optical properties, particularly the polarized response in two-dimensional (2D) materials, and provide a strategy for developing flexible and anisotropic 2D optical devices.

Graphical abstract: Strain manipulation of the polarized optical response in two-dimensional GaSe layers

Article information

Article type
Paper
Submitted
23 Oct 2019
Accepted
18 Jan 2020
First published
22 Jan 2020

Nanoscale, 2020,12, 4069-4076

Strain manipulation of the polarized optical response in two-dimensional GaSe layers

J. Zhou, Y. Wu, H. Wang, Z. Wu, X. Li, W. Yang, C. Ke, S. Lu, C. Zhang and J. Kang, Nanoscale, 2020, 12, 4069 DOI: 10.1039/C9NR09057F

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