本研究目的在探討六方氮化硼(hexagonal boron nitride, h-BN)作為間隔層，其厚度變化對侷域表面電漿(localized surface plasmon, LSP)結構之光學性質影響，並進一步了解其對 TMDC(如:WSe2與 MoS2)激子與金屬奈米粒子間耦合效率的調控效果。研究核心在於提升光致發光(PL)效率與增強LSP共振現象，以促進奈米光電元件之發展。
本研究使用機械剝離法取得單層 WSe2 與 MoS2，並轉移至含不同厚度 h-BN 的基板上製成異質結構，以奈米銀粒作為 LSP 來源。實驗部分透過光致發光量測、原子力顯微鏡(AFM)與光學顯微鏡分析樣品表面結構與發光特性；同時搭配 COMSOL 模擬，分析等效折射率、傳播距離、波導侷限係數、模態體積與雷射閾值增益等參數，深入探討不同 h-BN 厚度對光場分佈與侷限性的影響。
實驗結果顯示，適當厚度的 h-BN 能有效減少非輻射淬滅效應，提升激子與 LSP 的交互作用效率，進而增強 PL 訊號。模擬分析也指出，h-BN 厚度會影響電場集中度與模態體積，從而改變耦合強度與共振行為。整體而言，約 10 ~ 20 nm範圍的 h-BN 厚度最有利於 LSP 與激子的強耦合，為未來設計高效率、低功耗的奈米光電元件提供關鍵指引。

This research systematically investigates the influence of hexagonal boron nitride (h-BN) spacer layer thickness on the optical performance and exciton–plasmon coupling behavior in heterostructures composed of two-dimensional (2D) transition metal dichalcogenides (TMDCs) and silver nanoparticles. By employing monolayer WSe2 and MoS2 as the excitonic materials and incorporating AgNPs as localized surface plasmon (LSP) sources, we fabricated a series of heterostructures with varying h-BN thicknesses to explore their effect on photoluminescence (PL) enhancement and electromagnetic field confinement. Both experimental and simulation approaches were utilized to gain comprehensive insight into the interactions within these nanostructures.
Experimentally, samples were prepared via mechanical exfoliation of TMDCs, followed by transfer onto SiO2/Si substrates pre-coated with h-BN films of different thicknesses. AgNPs were subsequently deposited to induce LSP resonance. Optical characterization was performed using PL spectroscopy, atomic force microscopy (AFM), and optical microscopy. Meanwhile, numerical simulations using COMSOL Multiphysics provided insights into parameters such as effective refractive index, propagation length, mode volume, waveguide confinement factor, and laser threshold gain.
Results demonstrate that appropriate h-BN thickness is crucial for achieving strong exciton–plasmon coupling while minimizing non-radiative quenching. Thinner h-BN layers (~5–10 nm) were found to significantly enhance PL intensity, indicating improved coupling efficiency and optimal field overlap. In contrast, excessively thick h-BN layers reduced the field strength experienced by the TMDCs, leading to diminished enhancement. Simulations corroborated experimental trends and revealed that thin h-BN not only maximized electric field localization but also minimized mode volume and threshold gain, which are essential for applications such as plasmonic nanolasers.
This study highlights the importance of spacer layer engineering in exciton–plasmon systems and provides a critical guideline for designing highly efficient, low-power optoelectronic devices. The findings can be applied in the development of quantum light sources, plasmon-enhanced sensors, and compact photonic circuits.

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