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<p>Hexagonal boron nitride (hBN) is an ideal candidate for vacuum ultraviolet (VUV) photodetection owing to its ultra-wide bandgap, ultrahigh band-edge absorption coefficient, and excellent chemical and thermal stability, yet its intrinsic carrier transport anisotropy severely limits the performance of hBN-based photodetectors. In this work, the hBN nanosheet (BNNS) films were prepared via liquid-phase exfoliation and self-assembly technology, and three types of detectors with differentiated electrode structures were constructed: back interdigitated (PD 1), vertical interleaved (PD 2), and vertical cross (PD 3). The results show that PD 1 fully exploits the high in-plane carrier mobility of hBN and its unobstructed photosensitive area, achieving the optimal comprehensive photodetection performance with a responsivity of 1.03 mA/W at 185 nm and rise/fall times of 148.75/107.69 ms. In contrast, the vertically structured devices (PD 2 and PD 3) exhibit ultra-low pA-level dark current due to the suppressed out-of-plane carrier transport of hBN, but suffer from significant attenuation of photocurrent and response speed. DFT simulations reveal that in-plane electric fields induce band bending and charge delocalization in hBN to enable efficient carrier drift transport, while vertical electric fields fail to enhance interlayer electronic coupling owing to the weak van der Waals interactions between hBN layers, which constitute the fundamental bottleneck for out-of-plane carrier transport. This study uncovers the microscopic essence of the anisotropic carrier transport in hBN, providing a clear scientific paradigm for the structural optimization of high-performance VUV detectors.</p>

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Mechanism of photocarrier transport in vacuum ultraviolet photodetector based on hexagonal boron nitride nanosheets

  • 期刊论文

  • 发表日期：

    2026年6月18日

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  • Wannian Fang,
  • Qiang Li,
  • Ransheng Chen,
  • Youwei Chen,
  • Jiaxing Li,
  • Haifeng Liu,
  • Ziyan Lin,
  • Jing Ning,
  • Yue Hao

摘要

Hexagonal boron nitride (hBN) is an ideal candidate for vacuum ultraviolet (VUV) photodetection owing to its ultra-wide bandgap, ultrahigh band-edge absorption coefficient, and excellent chemical and thermal stability, yet its intrinsic carrier transport anisotropy severely limits the performance of hBN-based photodetectors. In this work, the hBN nanosheet (BNNS) films were prepared via liquid-phase exfoliation and self-assembly technology, and three types of detectors with differentiated electrode structures were constructed: back interdigitated (PD 1), vertical interleaved (PD 2), and vertical cross (PD 3). The results show that PD 1 fully exploits the high in-plane carrier mobility of hBN and its unobstructed photosensitive area, achieving the optimal comprehensive photodetection performance with a responsivity of 1.03 mA/W at 185 nm and rise/fall times of 148.75/107.69 ms. In contrast, the vertically structured devices (PD 2 and PD 3) exhibit ultra-low pA-level dark current due to the suppressed out-of-plane carrier transport of hBN, but suffer from significant attenuation of photocurrent and response speed. DFT simulations reveal that in-plane electric fields induce band bending and charge delocalization in hBN to enable efficient carrier drift transport, while vertical electric fields fail to enhance interlayer electronic coupling owing to the weak van der Waals interactions between hBN layers, which constitute the fundamental bottleneck for out-of-plane carrier transport. This study uncovers the microscopic essence of the anisotropic carrier transport in hBN, providing a clear scientific paradigm for the structural optimization of high-performance VUV detectors.