Fabrication and Characterization of Surfaceenhanced Raman Scattering Substrates With Ordered Arrays of Gold Nanopyramids By Means of Nanosphere Lithography

• Published in: Materials express 2019-04, Vol.9 (2), p.141-149
• Main Authors: Salinas, Cecilia, Rodríguez-Sevilla, Erika, Flores-Romero, Erick, Cheang-Wong, Juan-Carlos
• Format: Article
• Language: English
• Subjects: Arrays; Au Nanopyramids; Gold; Lithography; Nanosphere Lithography; Nanospheres; Ordered Arrays; Raman spectra; Rhodamine 6G; SERS; Silicon dioxide; Silicon substrates; Sol-gel processes; Thin films
• ISSN: 2158-5849; 2158-5857
• DOI: 10.1166/mex.2019.1476

In this work we combine the techniques of nanosphere lithography (NSL) and thermal evaporative patterning to fabricate gold nanostructures that can be used as substrates for Surface-Enhanced Raman Scattering (SERS). Spherical submicrometer-sized silica particles were prepared according to the sol-gel method and deposited as a monolayer onto silicon and silica plates, in order to use it as a mask to create regular arrays of triangle-based Au nanopyramids after a 50 nm thick Au film thermal evaporation. Rhodamine 6G, a dye molecule, was chosen as the SERS probe molecule to determine the enhancement factor of the Raman signal intensity. We studied the SERS performance of the system consisting of the Au nanopyramid arrays in comparison with a pure Au thin film evaporated onto a Si substrate, previously dipped in R6G in the same conditions. The results indicate that the sensing capabilities of the nanostructured sample are several orders of magnitude higher when compared with those exhibited by the gold thin films. Indeed, a SERS enhancement factor as large as approximately 1 × 106 can be achieved for the 1650 cm-1 Raman signal obtained with different excitation laser wavelengths (532 and 780 nm). Therefore, we can conclude that these combined techniques allow the fabrication of highly reproducible and ultrasensitive detecting SERS substrates.