Single Nanoparticle-Based Heteronanojunction as a Plasmon Ruler for Measuring Dielectric Thin Films.
Single Nanoparticle-Based Heteronanojunction as a Plasmon Ruler for Measuring Dielectric Thin Films.
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DOI：
10.1021/acs.jpclett.5b00806
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发表时间：
2015-06
期刊：
影响因子：
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通讯作者：
Li Li-Li;T. Hutter;Wenwu Li;S. Mahajan
中科院分区：
文献类型：
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作者：
Li Li-Li;T. Hutter;Wenwu Li;S. Mahajan
非破坏性的，非侵入性的和精确的测量薄膜厚度的介质基板上是具有挑战性的。在这项工作中，用于测量薄膜厚度的标尺利用在等离子体纳米颗粒和高折射率非等离子体基底之间形成的异质纳米结构造。纳米结的高近场灵敏度使其适用于测量介电薄膜的厚度。我们证明了这一点，通过控制的电介质间隔层的厚度，通过过度生长的二氧化硅薄膜上市售的硅基板。虽然瑞利（使用暗场）散射测量表明，光谱响应与SiO2间隔层的厚度很好地相关，但表面增强拉曼散射（Sers）的距离依赖性要陡得多。3D模拟和实验结果之间的良好一致性证实了等离子体标尺构造对电介质薄膜间距的敏感性。因此，我们假设这种基于单个纳米颗粒的异质纳米结配置可以用作薄膜计量中的方便且简单的标尺以及用于基于SERS的检测的平台，即使在等离子体激元活性膜不是合适的衬底的情况下。
Nondestructive, noninvasive and accurate measurement of thin film thicknesses on dielectric substrates is challenging. In this work a ruler for measuring thin film thicknesses utilizes the heteronanojunction construct formed between a plasmonic nanoparticle and a high refractive index nonplasmonic substrate. The high near-field sensitivity in the nanojunction renders it suitable for measuring the thickness of intervening dielectric thin films. We demonstrate this by controlling the thickness of dielectric spacer layers created by overgrowing SiO2 thin films on commercially available silicon substrates. While Rayleigh (using dark-field) scattering measurements show that the spectral response is well correlated to the thickness of SiO2 spacer layers the distance-dependence is much steeper with surface-enhanced Raman scattering (SERS). Good agreement between 3D simulations and experimental results confirm the plasmon ruler construct's sensitivity to the dielectric thin film spacing. Thus, we postulate that this single nanoparticle based heteronanojunction configuration can serve as a convenient and simple ruler in metrology of thin films as well as a platform for SERS-based detection even in cases where plasmonically active films are not a suitable substrate.