Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77843, United States.
Nano Lett. 2012 Sep 12;12(9):4881-8. doi: 10.1021/nl302428z. Epub 2012 Aug 13.
Herein, a new and facile patterning method is demonstrated for the scalable fabrication of gold elliptical rings (ERs) in a controlled manner over large areas. In this method, well-ordered hexagonally arrayed polystyrene (PS) rings, fabricated by colloidal lithography, were used as masters to generate poly(dimethylsiloxane) (PDMS) stamps with circular apertures. The stamps were then stretched and utilized as molds for creating elliptical PS rings by a capillary filling process. Through subsequent reactive ion etching and chemical wet-etching, the elliptical PS rings could be readily transferred into an underlying gold film, leading to the formation of gold ERs. Since the aspect ratio (AR) of the elliptical PS rings could be controlled by varying the applied strain during the capillary filling process, gold ERs with different ARs could be fabricated in a scalable manner. The optical properties of the gold ERs were characterized by UV-vis/NIR and IR extinction measurements. The ERs exhibited only odd modes of polarization-dependent plasmonic resonances at normal incidence. The experiments and corresponding theoretical studies illustrated that all resonant modes could be tuned across a broad spectral range from the visible to the mid infrared (550-4700 nm) by simply varying the AR of the ERs. Moreover, the experimental data were confirmed by COMSOL simulations.
本文展示了一种新的简易图案化方法，可在大面积上以可控的方式规模化制备金椭圆环（ER）。在该方法中，采用胶体光刻技术制备的有序六边形聚苯乙烯（PS）环被用作母版，以生成具有圆形孔的聚二甲基硅氧烷（PDMS）印章。然后将印章拉伸并用作通过毛细填充过程制造椭圆 PS 环的模具。通过后续的反应离子刻蚀和化学湿法刻蚀，可以将椭圆 PS 环很容易地转移到下面的金膜上，从而形成金 ER。由于椭圆 PS 环的纵横比（AR）可以通过在毛细填充过程中施加的应变来控制，因此可以以可扩展的方式制造具有不同 AR 的金 ER。通过紫外可见/近红外和红外消光测量对金 ER 的光学性质进行了表征。ER 在正常入射下仅表现出偏振相关等离子体共振的奇数模式。实验和相应的理论研究表明，通过简单地改变 ER 的 AR，所有共振模式都可以在从可见光到中红外（550-4700nm）的宽光谱范围内进行调节。此外，实验数据得到了 COMSOL 模拟的证实。
