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Graphene nanoribbon heterojunctions


Despite graphene's remarkable electronic properties1,2, the lack of an electronic bandgap severely limits its potential for applications in digital electronics3,4. In contrast to extended films, narrow strips of graphene (called graphene nanoribbons) are semiconductors through quantum confinement5,6, with a bandgap that can be tuned as a function of the nanoribbon width and edge structure7,8,9,10. Atomically precise graphene nanoribbons can be obtained via a bottom-up approach based on the surface-assisted assembly of molecular precursors11. Here we report the fabrication of graphene nanoribbon heterojunctions and heterostructures by combining pristine hydrocarbon precursors with their nitrogen-substituted equivalents. Using scanning probe methods, we show that the resulting heterostructures consist of seamlessly assembled segments of pristine (undoped) graphene nanoribbons (p-GNRs) and deterministically nitrogen-doped graphene nanoribbons (N-GNRs), and behave similarly to traditional p–n junctions12. With a band shift of 0.5 eV and an electric field of 2 × 108 V m–1 at the heterojunction, these materials bear a high potential for applications in photovoltaics and electronics.

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Figure 1: Bottom-up fabrication of N-GNRs.
Figure 2: Fabrication and identification of p-N-GNR heterojunctions.
Figure 3: Band offset across p-N-GNR heterojunctions.
Figure 4: Differential conductance dI/dV maps of p-N-GNR heterostructures.

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This work was supported by the Swiss National Science Foundation, by the State Secretariat for Education, Research and Innovation via the COST Action MP0901 ‘NanoTP’, by the European Science Foundation under the EUROCORES Program EuroGRAPHENE (GOSPEL), ERC NANOGRAPH, EU GENIUS project, Graphene Flagship and by the Office of Naval Research BRC Program. The Swiss Supercomputing Center, CSCS, is acknowledged for computational support (project s507). The authors thank D. Passerone for stimulating discussion. J.C. thanks R. Widmer, J. Liu and C. Sánchez for help with the experiments.

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Authors and Affiliations



J.C., P.R, R.F., X.F. and K.M. conceived and designed the experiments. R.B. synthesized the molecular precursors. J.C. performed the growth and scanning-probe experiments. J.C. and H.S. did the scanning tunnelling spectroscopy analysis. R.L. and X.F. developed the transfer process and performed the Raman measurements. C.A.P., L.T., L.L. and V.M. performed the simulations. J.C. and R.F. prepared the figures and wrote the paper. All authors discussed the results and implications, and commented on the manuscript.

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Correspondence to Klaus Müllen or Roman Fasel.

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The authors declare no competing financial interests.

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Cai, J., Pignedoli, C., Talirz, L. et al. Graphene nanoribbon heterojunctions. Nature Nanotech 9, 896–900 (2014).

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