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In-situ quantification of the surface roughness for facile fabrications of atomically smooth thin films

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Abstract

This work presents an in-situ technique to quantify the layer-by-layer roughness of thin films and heterostructures by measuring the spectral profile of the reflection high-energy electron diffraction (RHEED). The characteristic features of the diffraction spot, including the vertical to lateral size ratio c/b and the asymmetrical ratio c1/c2 along the vertical direction, are found to be quantitatively dependent on the surface roughness. The quantitative relationships between them are established and discussed for different incident angles of high-energy electrons. As an example, the surface roughnesses of LaCoO3 films grown at different temperatures are obtained using such an in-situ technique, which are confirmed by the ex-situ atomic force microscopy. Moreover, the in-situ measured layer-by-layer roughness oscillations of two LaCoO3 films are demonstrated, revealing drastically different information from the intensity oscillations. The experiments assisted with the in-situ technique demonstrate an outstanding high resolution down to ∼ 0.1 Å. Therefore, the new quantitative RHEED technique with real-time feedbacks significantly escalates the thin film synthesis efficiency, especially for achieving atomically smooth surfaces and interfaces. It opens up new prospects for future generations of thin film growth, such as the artificial intelligence-assisted thin film growth.

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Acknowledgements

The work was supported by the National Science Foundation of China (No. 52072244), the ShanghaiTech Startup Fund, and the Fundamental Research Funds for the Central Universities (No. WK2340000088).

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Authors and Affiliations

  1. Hefei National Laboratory for Physical Science at Microscale, Department of Physics, University of Science and Technology of China, Hefei, 230026, China

    Genhao Liang, Junkun Zha, Jingxian Zhang, Qixin Liu & Xiaofang Zhai

  2. School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China

    Genhao Liang, Long Cheng, Junkun Zha, Jingxian Zhang, Qixin Liu, Mingrui Bao, Jia Liu & Xiaofang Zhai

  3. X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA

    Hui Cao

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  1. Genhao Liang
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  2. Long Cheng
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Correspondence to Long Cheng or Xiaofang Zhai.

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Liang, G., Cheng, L., Zha, J. et al. In-situ quantification of the surface roughness for facile fabrications of atomically smooth thin films. Nano Res. 15, 1654–1659 (2022). https://doi.org/10.1007/s12274-021-3720-5

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  • DOI: https://doi.org/10.1007/s12274-021-3720-5

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