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Light-emitting diodes by band-structure engineering in van der Waals heterostructures

Abstract

The advent of graphene and related 2D materials1,2 has recently led to a new technology: heterostructures based on these atomically thin crystals3. The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative differential resistance4, tunnelling transistors5, photovoltaic devices6,7 and so on. Here, we take the complexity and functionality of such van der Waals heterostructures to the next level by introducing quantum wells (QWs) engineered with one atomic plane precision. We describe light-emitting diodes (LEDs) made by stacking metallic graphene, insulating hexagonal boron nitride and various semiconducting monolayers into complex but carefully designed sequences. Our first devices already exhibit an extrinsic quantum efficiency of nearly 10% and the emission can be tuned over a wide range of frequencies by appropriately choosing and combining 2D semiconductors (monolayers of transition metal dichalcogenides). By preparing the heterostructures on elastic and transparent substrates, we show that they can also provide the basis for flexible and semi-transparent electronics. The range of functionalities for the demonstrated heterostructures is expected to grow further on increasing the number of available 2D crystals and improving their electronic quality.

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Figure 1: Heterostructure devices with a SQW and MQWs.
Figure 2: Optical and transport characterization of our SQW devices, T = 7 K.
Figure 3: Optical and transport characteristics of MQW devices, T = 7 K.
Figure 4: Devices combining different QW materials and on flexible substrates.

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Acknowledgements

This work was supported by The Royal Society, Royal Academy of Engineering, US Army, European Science Foundation (ESF) under the EUROCORES Programme EuroGRAPHENE (GOSPEL), European Research Council, EC-FET European Graphene Flagship, Engineering and Physical Sciences Research Council (UK), the Leverhulme Trust (UK), US Office of Naval Research, US Defence Threat Reduction Agency, US Air Force Office of Scientific Research, FP7 ITN S3NANO, SEP-Mexico and CONACYT.

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Contributions

F.W. produced experimental devices, led the experimental part of the project, analysed experimental data, participated in discussions, contributed to writing the manuscript; O.D.P-Z. measured device characteristics, participated in discussions, analysed experimental data; A.M. measured transport properties of the devices, participated in discussions; A.P.R. and A.G. produced samples for TEM study, analysed TEM results, participated in discussions; K.W. and T.T. grew high-quality hBN, participated in discussions; S.J.H. analysed TEM results, participated in discussions; A.K.G. analysed experimental data, participated in discussions, contributed to writing the manuscript; A.I.T. analysed experimental data, participated in discussions, contributed to writing the manuscript; K.S.N. initiated the project, analysed experimental data, participated in discussions, contributed to writing the manuscript.

Corresponding author

Correspondence to K. S. Novoselov.

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The authors declare no competing financial interests.

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Withers, F., Del Pozo-Zamudio, O., Mishchenko, A. et al. Light-emitting diodes by band-structure engineering in van der Waals heterostructures. Nature Mater 14, 301–306 (2015). https://doi.org/10.1038/nmat4205

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