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- Title
In-plane optical and electrical anisotropy in low-symmetry layered GeS microribbons.
- Authors
Chen, Zhangfu; Hwang, Woohyun; Cho, Minhyun; Hoang, Anh Tuan; Kim, Minju; Kim, Dongwoo; Kim, Dong Ha; Kim, Young Duck; Kim, Hyun Jae; Ahn, Jong-Hyun; Soon, Aloysius; Choi, Heon-Jin
- Abstract
Layered group-IV monochalcogenides, including GeS, GeSe, SnS, and SnSe, garner attention because of their anisotropic structures and properties. Here, we report on the growth of GeS microribbons via chemical vapor transport (CVT), which affords each of them with a low-symmetry orthorhombic structure and anisotropic optical and electronic properties. The single-crystalline nature of the GeS microribbon, which has a typical thickness of ~30 nm, is confirmed. Polarized Raman spectra reveal angle-dependent intensities that are attributed to the anisotropic layered structure of GeS microribbons. The photoluminescence (PL) spectra reveal a peak at ~1.66 eV. The angle-dependent PL and anisotropic absorption spectroscopy results provide evidence for a distinct anisotropic optical transition near the energy band edges; this phenomenon is also predicted by our density functional theory (DFT)-based calculations. Strong in-plane direct-current transport anisotropy is observed under dark and white illumination by using back-gate cross-shaped field effect transistors (CSFETs) fabricated with the GeS microribbon; significant gate-tunable conductivity is also confirmed. The strong anisotropy is further confirmed by the DFT-calculated effective mass ratio. Our findings not only support the application of GeS microribbons in anisotropic photoelectronic transistors but also provide more possibilities for other functional device applications. Two-dimensional distorted orthorhombic GeS microribbons has been synthesized applying vapor-liquid-solid and vapor-solid mechanism-based chemical vapor transport. Polarized Raman and photoluminescence characterizations show the significantly angle-dependent intensity and anisotropic optical properties. Additionally, we probed the anisotropic electric properties by fabricating back-gate cross-shaped field effect transistors. In-plane direct current measurement demonstrated the charge carrier transport anisotropy and its anisotropic current ratio can be linearly adjusted by changing the gate voltage under dark and illumination conditions.
- Subjects
ANISOTROPY; CHALCOGENIDES; THICKNESS measurement; PHOTOLUMINESCENCE; FIELD-effect transistors
- Publication
NPG Asia Materials, 2022, Vol 14, Issue 1, p1
- ISSN
1884-4049
- Publication type
Article
- DOI
10.1038/s41427-022-00390-8