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Small contact resistance and low Schottky barrier height (SBH) are the keys to energy-efficient electronics and optoelectronics. Two-dimensional (2D) semiconductors-based field effect transistors (FETs), holding great promise for next-generation information circuits, still suffer from poor contact quality at the metal–semiconductor junction interface, which severely hinders their further applications. Here, a novel contact strategy is proposed, where Bi2Te3 nanosheets with high conductivity were in-situ epitaxially grown on MoS2 as van der Waals contacts, which can effectively avoid the damage to MoS2 caused during the device manufacturing process, leading to a high-performance MoS2 FET. Moreover, the small work function difference between Bi2Te3 and MoS2 (Bi2Te3: 4.31 eV, MoS2: 4.37 eV, measured by Kelvin probe force microscopy (KPFM)), enables small band bending and Ohmic contact at the junction interface. Electrical characterizations indicate that the MoS2 FET device with Bi2Te3 contacts possesses a high current on/off ratio (5 × 107), large effective carrier mobility (90 cm2/(V·s)), and low flat-band SBH (60 meV), which is favorable as compared with MoS2 FET with traditional Cr/Au electrodes contacts, and superior to the vast majority of the reported chemical vapor deposition (CVD) MoS2-based FET device. The demonstration of epitaxial van der Waals Bi2Te3 contacts will facilitate the application of 2D MoS2 nanosheet in next-generation low-power consumption electronics and optoelectronics.


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Epitaxial van der Waals contacts for low schottky barrier MoS2 field effect transistors

Show Author's information Huawei Liu1,2,§Lizhen Fang1,2,§Xiaoli Zhu1,2,§Chenguang Zhu1,2Xingxia Sun1,2Gengzhao Xu3Biyuan Zheng1,2Ying Liu1,2Ziyu Luo1,2Hui Wang1,2Chengdong Yao1,2Dong Li1,2( )Anlian Pan1,2( )
Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
Hunan Institute of Optoelectronic Integration, Hunan University, Changsha 410082, China
Suzhou Institute of Nano-tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China

§ Huawei Liu, Lizhen Fang, and Xiaoli Zhu contributed equally to this work.

Abstract

Small contact resistance and low Schottky barrier height (SBH) are the keys to energy-efficient electronics and optoelectronics. Two-dimensional (2D) semiconductors-based field effect transistors (FETs), holding great promise for next-generation information circuits, still suffer from poor contact quality at the metal–semiconductor junction interface, which severely hinders their further applications. Here, a novel contact strategy is proposed, where Bi2Te3 nanosheets with high conductivity were in-situ epitaxially grown on MoS2 as van der Waals contacts, which can effectively avoid the damage to MoS2 caused during the device manufacturing process, leading to a high-performance MoS2 FET. Moreover, the small work function difference between Bi2Te3 and MoS2 (Bi2Te3: 4.31 eV, MoS2: 4.37 eV, measured by Kelvin probe force microscopy (KPFM)), enables small band bending and Ohmic contact at the junction interface. Electrical characterizations indicate that the MoS2 FET device with Bi2Te3 contacts possesses a high current on/off ratio (5 × 107), large effective carrier mobility (90 cm2/(V·s)), and low flat-band SBH (60 meV), which is favorable as compared with MoS2 FET with traditional Cr/Au electrodes contacts, and superior to the vast majority of the reported chemical vapor deposition (CVD) MoS2-based FET device. The demonstration of epitaxial van der Waals Bi2Te3 contacts will facilitate the application of 2D MoS2 nanosheet in next-generation low-power consumption electronics and optoelectronics.

Keywords: mobility, heterojunction, Schottky barrier, transistors, van der Waals epitaxial

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Publication history
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Acknowledgements

Publication history

Received: 12 September 2022
Revised: 18 October 2022
Accepted: 19 October 2022
Published: 05 December 2022
Issue date: September 2023

Copyright

© Tsinghua University Press 2022

Acknowledgements

The authors are grateful to the National Key R&D Program of China (No. 2022YFA1402501), the National Natural Science Foundation of China (Nos. 51902098, 62090035, U22A2013, and U19A2090), the Key Program of Science and Technology Department of Hunan Province (Nos. 2019XK2001 and 2020XK2001), the Science and Technology Innovation Program of Hunan Province (Nos. 2021RC3061, 2020RC2028, and 2021RC2042), the Natural Science Foundation of Hunan Province (No. 2021JJ20016), and the Project funded by China Postdoctoral Science Foundation (Nos. 2020M680112 and 2021M690953).

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