Pronounced scale-dependent charge carrier density in graphene quantum Hall devices

Ziqiang Kong; Yu Feng; Han Gao; Ru Sun; Jian Feng; Chengxin Jiang; Chenxi Liu; Huishan Wang; Yu Zhang; Junchi Song; Xuanzheng Hao; Ziceng Zhang; Yuteng Ma; Shengda Gao; Ren Zhu; Qandeel Noor; Ghulam Ali; Yumeng Yang; Guanghui Yu; Shujie Tang; Zhongkai Liu; Haomin Wang

doi:10.1016/j.mtphys.2025.101928

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arXiv · 2511.19844

Pronounced scale-dependent charge carrier density in graphene quantum Hall devices

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Abstract

The miniaturization of quantum Hall resistance standards (QHRS) using epitaxial graphene on silicon carbide necessitates understanding how device dimensions impact performance. This study reveals a pronounced scale-dependent carrier density in graphene Hall devices: under electron doping, carrier density decreases with increasing channel width (Wd), while the opposite occurs under hole doping. This phenomenon, most significant for Wd less than 400 um, directly influences the onset of magnetic field required for quantization. Fermi velocity measurements and angle-resolved photoemission spectroscopy (ARPES) analysis indicate that band structure modifications and electron-electron interactions underlie this size dependence. Utilizing machine learning with limited data, we optimized the device geometry, identifying a channel width of ~360 um as the optimal balance between resistance uncertainty and on-chip integration density. This work provides key insights for designing high-performance, miniaturized graphene-based QHRS arrays.

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Ziqiang Kong, Yu Feng, Han Gao, Ru Sun, Jian Feng, Chengxin Jiang, Chenxi Liu, Huishan Wang, Yu Zhang, Junchi Song, Xuanzheng Hao, Ziceng Zhang, Yuteng Ma, Shengda Gao, Ren Zhu, Qandeel Noor, Ghulam Ali, Yumeng Yang, Guanghui Yu, Shujie Tang, Zhongkai Liu, Haomin Wang. 2025-11-25. Pronounced scale-dependent charge carrier density in graphene quantum Hall devices. https://doi.org/10.1016/j.mtphys.2025.101928

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