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  • Open Access

Order in disorder: Increased carrier mobility of downscaled amorphous semiconductors as exemplified by hydrogenated amorphous silicon

Yuezhou Luo* and Andrew John Flewitt

  • Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom

  • *Contact author: YL778@cantab.ac.uk
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Phys. Rev. Applied 24, 054065 – Published 21 November, 2025

DOI: https://doi.org/10.1103/n66s-qw44

Abstract

Amorphous semiconductors are important channel semiconductors in thin-film transistors (TFTs), which serve not only active-matrix displays, but also flexible electronics for Internet of things applications. Nevertheless, a great limitation of amorphous semiconductors is their low carrier mobilities relative to their monocrystalline counterparts. Based on a recently established band-fluctuation framework [Y. Luo and A. Flewitt, Phys. Rev. B 109, 104203 (2024)], this paper shows that the intrinsic carrier mobility of amorphous semiconductors can significantly increase simply through device downscaling, without any material-level optimizations. Specifically, it is revealed that the intrinsic electron mobility of hydrogenated amorphous silicon in a 10-nm-long gap can increase by about 12 times, and this does not compromise device-to-device uniformity. This mobility improvement is a result of reduced localized band-tail states due to the ultrashort gap length relative to the band-fluctuation length scale before downscaling; the latter is determined by the short- and medium-range structural order of the amorphous semiconductor.

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Phys. Rev. Applied 24, 054065– Published 21 November, 2025
  • Received 20 July 2025
  • Revised 19 September 2025
  • Accepted 17 October 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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