Templated Fabrication of Periodic Array of Nanovoids and Its SERS Performance

Qinghua Hong, Xuefeng Liu, Yun Fang
2013 Huaxue xuebao  
a 江南大学 化学与材料工程学院 无锡 214122) ( b 江南大学 食品胶体与生物技术教育部重点实验室 无锡 214122) 摘要 以内嵌在聚合物内、呈周期性非紧密接触方式排布的 SiO 2 微球阵列-聚合物复合薄膜为模板, 采用 HF 选择性 地蚀除复合薄膜表层 SiO 2 微球后, 便可便捷地得到单片面积达 182 cm 2 、 呈等边六边形周期性排布的有机球凹阵列, 每 个微球凹的容积约为 4.72 阿升(Attoliter, 1 Attoliter=10 -18 L), 球凹排布密度约为 4.9×10 8 球凹/cm 2 ; 镀金后的球凹阵 列可用作 SERS 活性基底, 以苯硫酚为探针的 SERS 结果表明, 球凹阵列的 Raman 信号增强因子(EF)高达 10 8 ~10 9 量 级, 在 182 cm 2 范围内 Abstract A facile and scalable fabrication method of highly periodic array of nano-sized voids with large area (182 cm 2 ) has
more » ... been achieved by means of a template related 3-step procedure. A non-close packed (NCP) colloidal SiO 2 array was fabricated by programmed spin-coating and in situ polymerization. The colloidal SiO 2 arrays are embedded in a polymer matrix, and the spheres of the top layer protrude out of the film, forming a periodic surface. After being etched by HF aqueous solution, the first layer of SiO 2 microspheres in the template were etched off and left behind a highly periodic hexagonal array of polymer nanovoids. The periodicity of the resulting polymer nanovoids array is the same as that of colloidal SiO 2 arrays. The volume of nanovoid is as small as about 4.72 attoliter per void, and the density of voids can be as high as about 4.9×10 8 voids/cm 2 . The metallic nanovoids array could be fabricated by subsequent deposition of Cr and Au layers. The resulting array of metallic nanovoids could be used as surface-enhanced Raman scattering (SERS) active substrates with ultrasensitivity and excellent reproducibility. The SERS performance of our nanovoids array was probed by benzenethoil. The SERS enhancement factor (EF) can be as high as in the order of 10 8 ~10 9 on average over 182 cm 2 . The mean relative standard deviation (RSD) of EF is in the range of 5.5% to 8.6% over 182 cm 2 which indicates the reproducibility of the substrates is quite good. The methodology leverages the high uniformity of the spin-coated colloidal arrays and well-established physical vapor deposition techniques. The formation of nanovoids array with high periodicity over large areas could lead to important technological applications in nanoelectronics and sensors.
doi:10.6023/a12110874 fatcat:cl5d47phxrgn3ogs2sjifpmduu