Optical second harmonic generation in encapsulated single-layer InSe

Leisgang, Nadine and Roch, Jonas G. and Froehlicher, Guillaume and Hamer, Matthew and Terry, Daniel and Gorbachev, Roman and Warburton, Richard J.. (2018) Optical second harmonic generation in encapsulated single-layer InSe. AIP Advances, 8 (10). p. 105120.

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We report the observation of optical second harmonic generation (SHG) in single-layer indium selenide (InSe). We measure a second harmonic signal of > 10 3 cts/s under nonresonant excitation using a home-built confocal microscope and a standard pulsed pico-second laser. We demonstrate that polarization-resolved SHG serves as a fast, non-invasive tool to determine the crystal axes in single-layer InSe and to relate the sharp edges of the flake to the armchair and zigzag edges of the crystal structure. Our experiment determines these angles to an accuracy better than ± 0.2◦. Treating the two-dimensional material as a nonlinear polarizable sheet, we determine a second-order sheet polarizability | χ (2) sheet | = (17.9 ± 11.0) × 10 − 20 m 2 V − 1 for single-layer InSe, corresponding to an effective nonlinear susceptibility value of | χ (2) eff |≈ (223 ± 138) × 10 − 12 m V − 1 accounting for the sheet thickness (d ≈ 0.8 nm). We demonstrate that the SHG technique can also be applied to encapsulated samples to probe their crystal orientations. The method is therefore suitable for creating high quality van der Waals heterostructures with control over the crystal directions.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimental Physics (Warburton)
UniBasel Contributors:Warburton, Richard J. and Leisgang, Nadine and Roch, Jonas Gael and Froehlicher, Guillaume, Marcel
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:AIP Publishing
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:26 Feb 2019 15:01
Deposited On:26 Feb 2019 15:01

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