Dependence of the optical constants and the performance in the SPREE gas measurement on the thickness of doped tin oxide over coatings
Dependence of the optical constants and the performance in the SPREE gas measurement on the thickness of doped tin oxide over coatings
复制标题
DOI：
10.1016/j.apsusc.2016.11.188
复制
发表时间：
2017-11-01
影响因子：
6.7
通讯作者：
Esser, N.
中科院分区：
文献类型：
--
作者：
Fischer, D.;Hertwig, A.;Esser, N.
在本研究中，研究了掺杂氧化锡光学性能与厚度相关的变化。制备了两组不同的样品。第一组是在硅衬底上掺杂铁或镍，厚度为29-56 nm，第二组是在金/玻璃衬底上掺杂铁，厚度为1.6-6.3 nm。通过使用光谱椭圆光度 (SE) 确定光学常数，然后通过使用高斯峰的振荡器模型对介电函数进行建模。光学常数的分析表明折射和吸收对掺杂氧化锡涂层的厚度的依赖性。除了紫外线中氧化锡的吸收之外，在近红外/红色中还发现了一个额外的吸收峰，这与掺杂引起的等离子体效应有关。该峰从近红外转移到可见光谱的红色部分，并通过减小厚度而变得更强，这可能是由于该层中金属纳米颗粒的形成所致。这些结果是使用相同的光学模型针对两组不同的样品得出的。随后，使用 CO 气体在表面等离子共振增强椭圆光度 (SPREE) 气体测量中对第二组样品进行了测试。结果发现，厚度对灵敏度以及 CO 气体的吸附有显着影响。通过将厚度从 1.6 nm 增加到 5.1 nm，由于表面涂层的覆盖率更高，传感能力得到增强。这是因为 CO 分子与氧化锡涂层中掺入的铁纳米颗粒具有高亲和力。当厚度进一步增加到 6.3 nm 时，传感能力会下降，因为该层对 SPR 传感效果的干扰太大。 (C) 2016 Elsevier B.V. 保留所有权利。
In this study, thickness related changes of the optical properties of doped tin oxide were studied. Two different sets of samples were prepared. The first set was doped with iron or nickel on silicon substrate with thicknesses of 29-56 nm, the second was iron doped on gold/glass substrate with 1.6-6.3 nm. The optical constants were determined by using spectral ellipsometry (SE) followed by modelling of the dielectric function with an oscillator model using Gaussian peaks. The analysis of the optical constants shows a dependence of the refraction and the absorption on the thickness of the doped tin oxide coating. In addition to the tin oxide absorption in the UV, one additional absorption peak was found in the near-IR/red which is related to plasmonic effects due to the doping. This peak shifts from the near-IR to the red part of the visible spectrum and becomes stronger by reducing the thickness, probably due to the formation of metal nanoparticles in this layer. These results were found for two different sets of samples by using the same optical model. Afterwards the second sample set was tested in the Surface Plasmon Resonance Enhanced Ellipsometric (SPREE) gas measurement with CO gas. It was found that the thickness has significant influence on the sensitivity and thus the adsorption of the CO gas. By increasing the thickness from 1.6 nm to 5.1 nm, the sensing ability is enhanced due to a higher coverage of the surface with the over coating. This is explained by the high affinity of CO molecules to the incorporated Fe-nanoparticles in the tin oxide coating. By increasing the thickness further to 6.3 nm, the sensing ability drops because the layer disturbs the SPR sensing effect too much. (C) 2016 Elsevier B.V. All rights reserved.