The family of group IV-VI monochalcogenides has an atomically puckered layered structure, and their atomic bond configuration suggests the possibility for the realization of various polymorphs. Here, we report the synthesis of the first hexagonal polymorph from the family of group IV-VI monochalcogenides, which is conventionally orthorhombic. Recently predicted four-atomic-thick hexagonal GeSe, so-called γ-GeSe, is synthesized and clearly identified by complementary structural characterizations, including elemental analysis, electron diffraction, high-resolution transmission electron microscopy imaging, and polarized Raman spectroscopy. The electrical and optical measurements indicate that synthesized γ-GeSe exhibits high electrical conductivity of 3 × 105 S/m, which is comparable to those of other two-dimensional layered semimetallic crystals. Moreover, γ-GeSe can be directly grown on h-BN substrates, demonstrating a bottom-up approach for constructing vertical van der Waals heterostructures incorporating γ-GeSe. The newly identified crystal symmetry of γ-GeSe warrants further studies on various physical properties of γ-GeSe.
Bibliographical noteFunding Information:
This work was mainly supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF-2017R1A5A1014862, NRF-2017R1C1B2012729, NRF-2019R1C1C1003643, 2020R1A2C3013673, and 2019R1A2C3006189) and by the Institute for Basic Science (IBS-R026-D1). Y.L. received support from the Basic Science Research Program at the National Research Foundation of Korea, which was funded by the Ministry of Education (NRF-2020R1A6A3A13060549), and Ministry of Science and ICT (NRF-2021R1C1C2006785). A.G. acknowledges the support from the Yonsei University Research Fund (Post-Doctoral Researcher Supporting Program) of 2019 (2019-12-0033). Computational resources were provided by the KISTI Supercomputing Center (Project No. KSC-2019-CRE-0195). Experiments at PLS-II were supported in part by MSIT and POSTECH.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering