通过界面电荷转移调控氧化物/石墨烯异质结构中的等离激元

中文摘要 AI 辅助

界面电荷转移是调控二维材料光学与电子性质的有效途径。本研究利用散射型扫描近场光学显微镜，探究氧化物/石墨烯异质结构中的红外表面等离激元极化激元。通过物理气相沉积制备的超薄氧化物覆盖层可通过界面电荷重分布系统地调控石墨烯等离激元：MoOx能显著增强等离激元响应，产生更长的等离激元波长、更强的条纹对比度及更低的阻尼；后续沉积的ZnOx覆盖层则部分逆转这些变化。结合定量建模的能量依赖型纳米红外成像揭示了石墨烯载流子密度的增加及由此产生的等离激元色散改变。厚度依赖测量显示，亚纳米级MoOx厚度下电荷转移掺杂快速增加，覆盖层厚度更大时则呈现较弱的长程贡献。静电栅压可进一步调制载流子密度，产生与栅压依赖型界面电荷重分布一致的非线性响应。此外，约3nm厚的MoOx覆盖层可在环境条件下稳定等离激元响应至少7个月。这些结果确立了氧化物/石墨烯异质结构为兼容可规模化制备的稳健平台，为稳定且可调谐的红外纳米光子及光电器件提供了途径。

英文摘要

Interfacial charge transfer provides an effective route for tailoring the optical and electronic properties of two-dimensional materials. Here, we investigate infrared surface plasmon polaritons in oxide/graphene heterostructures using scattering-type scanning near-field optical microscopy. Ultrathin oxide overlayers deposited by physical vapor deposition enable systematic engineering of graphene plasmons through interfacial charge redistribution. MoOx strongly enhances the plasmonic response, producing a longer plasmon wavelength, stronger fringe contrast, and reduced damping, whereas a subsequently deposited ZnOx overlayer partially reverses these changes. Energy-dependent nano-infrared imaging combined with quantitative modeling reveals an increased graphene carrier density and the resulting modification of the plasmon dispersion. Thickness-dependent measurements show a rapid increase in charge-transfer doping at sub-nanometer MoOx thicknesses, followed by a weaker long-range contribution at larger overlayer thicknesses. Electrostatic gating further modulates the carrier density and produces a nonlinear response consistent with gate-dependent interfacial charge redistribution. In addition, an approximately 3-nm-thick MoOx overlayer stabilizes the plasmonic response for at least seven months under ambient conditions. These results establish oxide/graphene heterostructures as a robust platform compatible with scalable fabrication, providing a pathway toward stable and tunable infrared nanophotonic and optoelectronic devices.

补充信息

备注

17 pages, 7 figures