Remote epitaxy of single-crystal rhombohedral WS2 bilayers

Chao Chang; Xiaowen Zhang; Weixuan Li; Quanlin Guo; Zuo Feng; Chen Huang; Yunlong Ren; Yingying Cai; Xu Zhou; Jinhuan Wang; Zhilie Tang; Feng Ding; Wenya Wei; Kaihui Liu; Xiaozhi Xu

doi:10.1038/s41467-024-48522-8

Remote epitaxy of single-crystal rhombohedral WS₂ bilayers

Nat Commun. 2024 May 16;15(1):4130. doi: 10.1038/s41467-024-48522-8.

Authors

Chao Chang^#^{1

2}, Xiaowen Zhang^#^{1

2}, Weixuan Li^#^{1

2}, Quanlin Guo^#³, Zuo Feng^#³, Chen Huang³, Yunlong Ren^{1

2

4}, Yingying Cai^{1

2}, Xu Zhou^{1

2}, Jinhuan Wang^{1

2}, Zhilie Tang^{1

2}, Feng Ding⁵, Wenya Wei^{6

7}, Kaihui Liu^{8

9

10}, Xiaozhi Xu^{11

12}

Affiliations

¹ Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China.
² Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China.
³ State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China.
⁴ Songshan Lake Materials Laboratory, Institute of Physics, Chinese Academy of Sciences, Dongguan, 523808, China.
⁵ Faculty of Materials Science and Engineering/Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
⁶ Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China. wywei2021@m.scnu.edu.cn.
⁷ Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China. wywei2021@m.scnu.edu.cn.
⁸ State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China. khliu@pku.edu.cn.
⁹ Songshan Lake Materials Laboratory, Institute of Physics, Chinese Academy of Sciences, Dongguan, 523808, China. khliu@pku.edu.cn.
¹⁰ Interdisciplinary Institute of Light-Element Quantum Materials and Research Centre for Light-Element Advanced Materials, Peking University, 100871, Beijing, China. khliu@pku.edu.cn.
¹¹ Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China. xiaozhixu@scnu.edu.cn.
¹² Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China. xiaozhixu@scnu.edu.cn.

^# Contributed equally.

Abstract

Compared to transition metal dichalcogenide (TMD) monolayers, rhombohedral-stacked (R-stacked) TMD bilayers exhibit remarkable electrical performance, enhanced nonlinear optical response, giant piezo-photovoltaic effect and intrinsic interfacial ferroelectricity. However, from a thermodynamics perspective, the formation energies of R-stacked and hexagonal-stacked (H-stacked) TMD bilayers are nearly identical, leading to mixed stacking of both H- and R-stacked bilayers in epitaxial films. Here, we report the remote epitaxy of centimetre-scale single-crystal R-stacked WS₂ bilayer films on sapphire substrates. The bilayer growth is realized by a high flux feeding of the tungsten source at high temperature on substrates. The R-stacked configuration is achieved by the symmetry breaking in a-plane sapphire, where the influence of atomic steps passes through the lower TMD layer and controls the R-stacking of the upper layer. The as-grown R-stacked bilayers show up-to-30-fold enhancements in carrier mobility (34 cm²V^-1s^-1), nearly doubled circular helicity (61%) and interfacial ferroelectricity, in contrast to monolayer films. Our work reveals a growth mechanism to obtain stacking-controlled bilayer TMD single crystals, and promotes large-scale applications of R-stacked TMD.