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sp2 to sp3 hybridization transformation in 2D metal-semiconductor contact interface suppresses tunneling barrier and Fermi level pinning simultaneously

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Van der Waals (vdWs) stacking of two-dimensional (2D) materials can effectively weaken the Fermi level pinning (FLP) effect in metal/semiconductor contacts due to dangling-bond-free surfaces. However, the inherent vdWs gap always induces a considerable tunneling barrier, significantly limiting carrier injection. Herein, by inducing a sp2 to sp3 hybridization transformation in 2D carbon-based metal via surface defect engineering, the large orbital overlap can form an efficient carrier channel, overcoming the tunneling barrier. Specifically, by selecting the 2D carbon-based X3C2 (X = Cd, Hg, and Zn) metal and the 2D MSi2N4 (M = Cr, Hf, Mo, Ti, V, and Zr) semiconductor, we constructed 36 metal/semiconductor contacts. For vdWs contacts, although Ohmic contacts can be formed at the interface, the highest tunneling probability (PTB) is only 3.11%. As expected, the PTB can be significantly improved, as high as 48.73%, when MSi2N4, accompanied by surface nitrogen vacancies, forms an interface covalent bond with X3C2. Simultaneously, weak FLP and Ohmic contact remain at the covalent-bond-based surface, attributing to the protection of the MSi2N4 band-edge electronic states by the outlying Si-N sublayer. Our work provides a promising path for advancing the progress of 2D electronic and photoelectronic devices.

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Acknowledgements

This work is supported by China Postdoctoral Science Foundation (No. 2022M711691), the National Natural Science Foundation of China (Nos. 12104130 and 12304085), Six talent peaks project in Jiangsu Province (No. XCL-104), the open research fund of Key Laboratory of Quantum Materials and Devices (Southeast University), Ministry of Education (No. 3207022401C3), and Natural Science Foundation of Nanjing University of Posts and Telecommunications (No. NY221102).

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Authors and Affiliations

  1. School of Science, State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM) and College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing, 210023, China

    Wenchao Shan, Anqi Shi, Zhuorong Zhong, Yongtao Li & Xianghong Niu

  2. College of Physics Science and Technology, Yangzhou University, Yangzhou, 225002, China

    Xiuyun Zhang

  3. Institute for Computational Materials Science, Joint Center for Theoretical Physics (JCTP), School of Physics and Electronics, Henan University, Kaifeng, 475004, China

    Bing Wang

  4. Key Laboratory of Quantum Materials and Devices (Southeast University), Ministry of Education, Nanjing, 211189, China

    Xianghong Niu

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  1. Wenchao Shan
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  2. Anqi Shi
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Correspondence to Bing Wang, Yongtao Li or Xianghong Niu.

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sp2 to sp3 hybridization transformation in 2D metal-semiconductor contact interface suppresses tunneling barrier and Fermi level pinning simultaneously

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Shan, W., Shi, A., Zhong, Z. et al. sp2 to sp3 hybridization transformation in 2D metal-semiconductor contact interface suppresses tunneling barrier and Fermi level pinning simultaneously. Nano Res. 17, 10227–10234 (2024). https://doi.org/10.1007/s12274-024-6877-x

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