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Large second-order susceptibility from a quantized indium tin oxide monolayer

Nature Nanotechnology volume 19, pages 463–470 (2024)Cite this article

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Abstract

Due to their high optical transparency and electrical conductivity, indium tin oxide thin films are a promising material for photonic circuit design and applications. However, their weak optical nonlinearity has been a substantial barrier to nonlinear signal processing applications. In this study, we show that an atomically thin (~1.5 nm) indium tin oxide film in the form of an air/indium tin oxide/SiO2 quantum well exhibits a second-order susceptibility χ2 of ~1,800 pm V–1. First-principles calculations and quantum electrostatic modelling point to an electronic interband transition resonance in the asymmetric potential energy of the quantum well as the reason for this large χ2 value. As the χ2 value is more than 20 times higher than that of the traditional nonlinear LiNbO3 crystal, our indium tin oxide quantum well design can be an important step towards nonlinear photonic circuit applications.

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Fig. 1: Second-order nonlinearity in van der Waals 2D ITO films.
Fig. 2: Characterization of 2D ITO samples.
Fig. 3: Experimental verification of the 2D-ITO-based asymmetric QW.
Fig. 4: Theoretical analysis on the 2D ITO QW.

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Data availability

All related data generated and/or analysed in this study are available from the corresponding authors on reasonable request. Source data are provided with this paper.

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Acknowledgements

The work at Zhejiang University was sponsored by the National Key Research and Development Program of China under grant no. 2021YFB2801801 and the National Natural Science Foundation of China (NNSFC) under grant nos 62005237 and 62175217. We acknowledge the Zhejiang University Micro-Nano Fabrication Center for providing the facilities and assistance.

Author information

Author notes

  1. These authors contributed equally: Yiyun Zhang, Bingtao Gao.

Authors and Affiliations

  1. Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China

    Yiyun Zhang, Bingtao Gao, Wendi Xia, Junru Niu, Yiming Feng, Hongsheng Chen & Haoliang Qian

  2. International Joint Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang, Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, China

    Yiyun Zhang, Bingtao Gao, Wendi Xia, Junru Niu, Yiming Feng, Hongsheng Chen & Haoliang Qian

  3. Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, China

    Yiyun Zhang, Bingtao Gao, Wendi Xia, Junru Niu, Yiming Feng, Hongsheng Chen & Haoliang Qian

  4. Institut Quantique, Université de Sherbrooke, Sherbrooke, Quebec, Canada

    Dominic Lepage

  5. State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China

    Yuanbiao Tong & Pan Wang

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  1. Yiyun Zhang
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Contributions

H.Q. conceived the idea. Y.Z. conducted the theoretical modelling and optical measurements. B.G., Y.T. and P.W. performed the material fabrication and characterization. Y.Z., B.G., D.L. and H.Q. contributed extensively to the writing of the manuscript. Y.Z., B.G., D.L., W.X., J.N., Y.F., H.C. and H.Q. analysed data and interpreted the details of the results. H.C. and H.Q. supervised the research.

Corresponding authors

Correspondence to Hongsheng Chen or Haoliang Qian.

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Nature Nanotechnology thanks Kai-Qiang Lin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–14, Notes 1–15 and Tables 1 and 2.

Source data

Source Data Fig. 1

Calculated dipole moment and measured reflectance data for different ITO/substrate samples.

Source Data Fig. 2

AFM data and optical measurement for 2D ITO.

Source Data Fig. 3

Second-order-nonlinearity-related optical measurement data for 2D ITO.

Source Data Fig. 4

Energy level number relation for ITO-based QW and wavelength- and angle-dependent optical measurements.

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Zhang, Y., Gao, B., Lepage, D. et al. Large second-order susceptibility from a quantized indium tin oxide monolayer. Nat. Nanotechnol. 19, 463–470 (2024). https://doi.org/10.1038/s41565-023-01574-1

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