Carbon materials such as graphene are of potential use in the development of electronic devices because of properties such as high mechanical strength and electrical and thermal conductivity. However, technical challenges, including difficulties in generating and modulating bandgaps, have limited the application of such materials. Here we show that the bandgaps of bilayers of two-dimensional C3N can be engineered by controlling the stacking order or applying an electric field. AA′ stacked C3N bilayers are found to have a smaller bandgap (0.30 eV) than AB′ stacked bilayers (0.89 eV), and both bandgaps are lower than that of monolayer C3N (1.23 eV). The larger bandgap reduction observed in AA′ stacked bilayers, compared with AB′ stacked bilayers, is attributed to the greater pz-orbital overlap. By applying an electric field of ~1.4 V nm−1, a bandgap modulation of around 0.6 eV can be achieved in the AB′ structure. We also show that the C3N bilayers can offer controllable on/off ratios, high carrier mobilities and photoelectric detection capabilities.
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The data that support the plots within this manuscript and other findings of this study are available from the corresponding authors upon reasonable request. Source data are provided with this paper.
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This work was financially supported by the National Natural Science Foundation of China (grants 21673075, 51725204, 21771132, 51972216, 52041202, 11774368, 11804353, 11704204, 61971035, 61901038 and 61725107), National Key Research and Development Program of China (2019YFA0308000, 2020YFA0308800 and 2020YFA0406104), Innovative Research Group Project of the National Natural Science Foundation of China (51821002), the Australian Research Council through the Discovery Early Career Research Program (DE170101403), Natural Science Foundation of Jiangsu Province (BK20190041), Key-Area Research and Development Program of GuangDong Province (2019B010933001), Collaborative Innovation Center of Suzhou Nano Science & Technology, the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the 111 Project. B.I.Y. thanks the Office of Naval Research (N00014−18-1-2182) and the Army Research Office (W911NF-16-1-0255) for support. W.W. was supported by a scholarship from the China Scholarship Council. The computations were performed at ECNU Multifunctional Platform for Innovation (001), Shanghai Supercomputer Center and using computational resources of the NCI through the National Computational Merit Allocation Scheme supported by the Australian Government, the Queensland Cyber Infrastructure Foundation and the University of Queensland Research Computing Centre. We thank D. Sun in East China Normal University for useful discussions.
The authors declare no competing interests.
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Wei, W., Yang, S., Wang, G. et al. Bandgap engineering of two-dimensional C3N bilayers. Nat Electron 4, 486–494 (2021). https://doi.org/10.1038/s41928-021-00602-z