Jung Lena, Hauer Benedikt, Li Peining, Bornhöfft Manuel, Mayer Joachim, Taubner Thomas
Opt Express. 2016 Mar 7;24(5):4431-4441. doi: 10.1364/OE.24.004431.
We present a study on subsurface imaging with an infrared scattering-type scanning near-field optical microscope (s-SNOM). The depth-limitation for the visibility of gold nanoparticles with a diameter of 50 nm under SiN is determined to about 50 nm. We first investigate spot size and signal strength concerning their particle-size dependence for a dielectric cover layer with positive permittivity. The experimental results are confirmed by model calculations and a comparison to TEM images. In the next step, we investigate spectroscopically also the regime of negative permittivity of the capping layer and its influence on lateral resolution and signal strength in experiment and simulations. The explanation of this observation combines subsurface imaging and superlensing, and shows up limitations of the latter regarding small structure sizes.
我们展示了一项使用红外散射型扫描近场光学显微镜（s-SNOM）进行地下成像的研究。确定了在氮化硅（SiN）下直径为50纳米的金纳米颗粒可见性的深度限制约为50纳米。我们首先研究了对于具有正介电常数的介电覆盖层，光斑尺寸和信号强度与颗粒尺寸的依赖关系。实验结果通过模型计算以及与透射电子显微镜（TEM）图像的比较得到了证实。在下一步中，我们还通过光谱研究了覆盖层负介电常数的区域及其在实验和模拟中对横向分辨率和信号强度的影响。对这一观察结果的解释结合了地下成像和超透镜效应，并显示了后者在小结构尺寸方面的局限性。
