Kulikova Daria P, Dobronosova Alina A, Kornienko Vladimir V, Nechepurenko Igor A, Baburin Aleksandr S, Sergeev Evgeny V, Lotkov Evgeniy S, Rodionov Ilya A, Baryshev Alexander V, Dorofeenko Alexander V
Opt Express. 2020 Oct 12;28(21):32049-32060. doi: 10.1364/OE.405403.
In recent years, we have been witnessing the intensive development of optical gas sensors. Thin palladium and platinum films as well as tungsten trioxide films with palladium or platinum catalysts are widely used for hydrogen detection, and the optical constants of these materials are required for sensor development. We report the optical parameters retrieved from a set of ellipsometric and transmission spectra for electron-beam evaporated palladium, platinum, and tungsten trioxide films. The tungsten trioxide films were 81 nm, 162 nm, and 515 nm thick and the metal films were as thin as 5-7 nm. Ultrathin palladium and platinum films were shown to be successfully described by local and isotropic permittivity, which is quite different from known bulk values. However, this permittivity showed a strong dependence on adjacent materials, thus illustrating that the ultrathin metallic films can be considered composites characterized by effective permittivity. With the obtained refractive indices and permittivities, the optical spectra of fabricated WO/Pd and WO/Pt nanostructures incorporating 1D grating of AlO were in an excellent agreement with the calculated ones without requiring any additional fitting procedures or inclusion of surface roughness layers in numerical models.
近年来，我们目睹了光学气体传感器的蓬勃发展。钯和铂薄膜以及带有钯或铂催化剂的三氧化钨薄膜被广泛用于氢气检测，而这些材料的光学常数对于传感器的开发至关重要。我们报告了从一组椭圆偏振光谱和透射光谱中获取的电子束蒸发钯、铂和三氧化钨薄膜的光学参数。三氧化钨薄膜的厚度分别为81纳米、162纳米和515纳米，金属薄膜薄至5 - 7纳米。超薄钯和铂薄膜已被证明可以用局部各向同性介电常数成功描述，这与已知的块状材料值有很大不同。然而，这种介电常数对相邻材料表现出强烈的依赖性，因此表明超薄金属薄膜可被视为具有有效介电常数特征的复合材料。利用所获得的折射率和介电常数，包含一维氧化铝光栅的制备的WO/Pd和WO/Pt纳米结构的光谱与计算光谱非常吻合，无需任何额外拟合程序或在数值模型中包含表面粗糙度层。
