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Graphene–MoS2 hybrid structures for multifunctional photoresponsive memory devices

Nature Nanotechnology volume 8, pages 826–830 (2013)Cite this article

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Abstract

Combining the electronic properties of graphene1,2 and molybdenum disulphide (MoS2)3,4,5,6 in hybrid heterostructures offers the possibility to create devices with various functionalities. Electronic logic and memory devices have already been constructed from graphene–MoS2 hybrids7,8, but they do not make use of the photosensitivity of MoS2, which arises from its optical-range bandgap9. Here, we demonstrate that graphene-on-MoS2 binary heterostructures display remarkable dual optoelectronic functionality, including highly sensitive photodetection and gate-tunable persistent photoconductivity. The responsivity of the hybrids was found to be nearly 1 × 1010 A W−1 at 130 K and 5 × 108 A W−1 at room temperature, making them the most sensitive graphene-based photodetectors. When subjected to time-dependent photoillumination, the hybrids could also function as a rewritable optoelectronic switch or memory, where the persistent state shows almost no relaxation or decay within experimental timescales, indicating near-perfect charge retention. These effects can be quantitatively explained by gate-tunable charge exchange between the graphene and MoS2 layers, and may lead to new graphene-based optoelectronic devices that are naturally scalable for large-area applications at room temperature.

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Figure 1: Device and optoelectronic response.
Figure 2: Photoresponsivity of graphene–MoS2 hybrid.
Figure 3: Gate- and intensity-dependent switching and relaxation.
Figure 4: Persistent photoconductivity mechanism.

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Acknowledgements

The authors acknowledge the Department of Science and Technology (DST) for a funded project under Nanomission. S.R. acknowledges support under grant no. SR/S2/CMP-02/2007 (DST).

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Author notes

  1. Srijit Goswami & Gopalakrishnan Ramalingam

    Present address: Present address: Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands (S.G.); Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904, USA (G.R.),

Authors and Affiliations

  1. Department of Physics, Indian Institute of Science, Bangalore, 560012, India

    Kallol Roy, Medini Padmanabhan, Srijit Goswami, T. Phanindra Sai & Arindam Ghosh

  2. Centre for Nano Science and Engineering and Materials Research Center, Indian Institute of Science, Bangalore, 560012, India

    Gopalakrishnan Ramalingam & Srinivasan Raghavan

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Contributions

K.R. and A.G. conceived and designed the experiments. K.R. and M.P. performed the experiments. K.R., M.P. and A.G. analysed the data. S.G., T.P.S. and K.R. developed the heterostructure fabrication technique used in the experiment. G.R. and S.R. contributed CVD graphene material. K.R., M.P. and A.G. co-wrote the paper. All authors discussed the results and commented on the manuscript.

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Correspondence to Kallol Roy or Arindam Ghosh.

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The authors declare no competing financial interests.

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Roy, K., Padmanabhan, M., Goswami, S. et al. Graphene–MoS2 hybrid structures for multifunctional photoresponsive memory devices. Nature Nanotech 8, 826–830 (2013). https://doi.org/10.1038/nnano.2013.206

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