[论文解读] Surface defects in carbon-doped hexagonal boron nitride for negative-contrast direct laser writing

D. Litvinov, Virgil Gavriliuc+6 more|arXiv (Cornell University)|Feb 14, 2026

Graphene research and applications被引用 0

一句话总结

这篇论文在碳掺杂的 hBN 中识别出表面局部化的辐射缺陷类别，该缺陷可通过激光淬灭调控并通过表面化学永久淬灭，从而实现对发射模式的负对比直接激光写入。

ABSTRACT

Radiative defects in hexagonal boron nitride (hBN) are active in a broad spectral range from deep ultraviolet to near-infrared wavelengths. Representatives of these defects act as bright single photon sources, spin-1 systems, and multiproperty atomic-scale sensors. They are predominantly investigated in bulk hBN films, where defects are decoupled from surface and interfacial effects. Here, we demonstrate a novel class of surface defects optically active in the green/yellow visible spectral range, which exhibit photophysical properties distinct from their bulk counterparts. High-power resonant laser illumination quenched the emission from the ensemble of such defects, which was attributed to a light-driven structural reconfiguration. The quenched defects were found to recover their emissive capabilities via a thermal cycling process, revealing an activation energy of 24.5 meV for the structural transition. Alternatively, permanent quenching of the defects was triggered by surface chemistry, involving lithiation-enabled attachment of functional groups. These mechanisms were utilized to realize negative-contrast direct laser writing, designing arbitrary geometric emissive patterns on demand in a microscopic configuration. The surface-active radiative centers in hBN appear particularly attractive for exploring environmental sensitivity, surface science, and coupling to photonic structures or electronic devices by taking unique advantage of the two-dimensional characteristics of the host lattice.

研究动机与目标

• Identify and characterize surface-localized radiative defects in carbon-doped hBN flakes.
• Differentiate surface defects from bulk defects and assess environmental sensitivity at surfaces.
• Demonstrate laser-induced reversible quenching and thermal recovery to reveal defect dynamics.
• Show permanent quenching via classical surface chemistry to confirm surface nature of defects.
• Demonstrate programmable negative-contrast direct laser writing of emissive patterns on hBN flakes.

提出的方法

• Mechanical exfoliation of carbon-doped hBN crystals to obtain flakes.
• Low-temperature photoluminescence (PL) and PL excitation (PLE) spectroscopy to identify defect A, B, and C.
• High-power resonant laser irradiation to induce PL quenching of surface defect A.
• Thermal cycling up to 300 K to study recovery and extract activation energy.
• Atomic force microscopy to relate PL to topography and edges.
• Chemical surface modification via lithiation with n-butyllithium followed by reaction with maleic anhydride to permanently quench defect A.

实验结果

研究问题

• RQ1 What are the optical and structural characteristics of surface defects in carbon-doped hBN distinct from bulk defects?
• RQ2 Can surface defects exhibit reversible laser-induced quenching, and what is the activation energy for recovery?
• RQ3 Is permanent quenching achievable via surface chemistry, confirming surface localization of these defects?
• RQ4 Can negative-contrast emissive patterns be written and read out at microscopic scales using these surface defects?
• RQ5 How do surface defects couple to phonons and respond to environmental and chemical modifications?

主要发现

• A distinct surface defect (defect A) in carbon-doped hBN shows photoluminescence that is quenched under high-power resonant laser excitation and can be partially recovered by thermal cycling.
• The recovery process follows a thermal activation with an activation energy of 24.5 meV for the radiative-to-nonradiative transition, indicating a light-driven structural reconfiguration.
• Permanent quenching of defect A is achieved through lithiation followed by attachment of an electrophilic moiety, confirming the surface nature of these defects and leaving bulk defects B and C unaffected.
• The quenching dynamics are biexponential, with readouts showing a few-second characteristic quenching times and a biexponential temperature dependence suggesting multiple reconstructed states.
• Direct laser writing demonstrates negative-contrast emissive patterns, with initial pattern contrast quantified by R initial = 0.95, quenched contrast R quenched = 0.05, and recovered contrast R recovered = 0.20.
• Defects B and C (bulk) show homogeneous PL and are less sensitive to surface chemistry, highlighting the unique surface-localized behavior of defect A.