Short-Wave Near-Infrared Linear Dichroism of Two-Dimensional Germanium Selenide.

Author(s) Wang, X.; Li, Y.; Huang, L.; Jiang, X.W.; Jiang, L.; Dong, H.; Wei, Z.; Li, J.; Hu, W.
Journal J Am Chem Soc
Date Published 2017 Sep 19

Polarized detection has been brought into operation for optics applications in visible band. Although an advanced requirement in short-wave near-infrared (SW-NIR) (700-1100 nm) is proposed, the approaching of this target remains under way. Theoretically, IV-VI chalcogenides two-dimensional (2D) structures, e.g., 2D germanium selenide (GeSe), possess anisotropic layered orthorhombic structure, narrow 1.1-1.2eV bandgap and potentially meet the demand. Here we report the unusual angle dependences of Raman spectra on controllably synthesized high-quality 2D GeSe crystals. The polarization-resolved absorption spectra (400-1200 nm) and polarization sensitive photodetectors (532, 638 and 808 nm) both exhibited well-reproducible cycle, distinct anisotropic feature and typical absorption ratio αb /αa ~ 1.08 at 532 nm, 1.26 at 633 nm, 3.02 at 808 nm (the dichroic ratio Ipb/Ipa ~ 1.09 at 532 nm, 1.44 at 633 nm, 2.16 at 808 nm). Obviously, the polarized measurement for GeSe showed superior anisotropic response around 808 nm within the SW-NIR band. Besides, the two testing methods have demonstrated the superior reliability for each other. For the layer dependence of LD, the GeSe samples with four different thickness at both 638 and 808 nm identify the best results can be achieved at about 8-16 nm.

DOI 10.1021/jacs.7b06314
ISSN 1520-5126
Citation J Am Chem Soc. 2017.

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