Fabrication of large area nanoprism arrays and their application for surface enhancedRaman spectroscopy

Abstract

This work demonstrates the fabrication of metallic nanoprism (triangular nanostructure)arrays using a low-cost and high-throughput process. In the method, the triangularstructure is defined by the shadow of a pyramid during angle evaporation of ametal etching mask. The pyramids were created by nanoimprint lithography inpolymethylmethacrylate (PMMA) using a mould having an inverse-pyramid-shaped holearray formed by KOH wet etching of silicon. Silver and gold nanoprism arrays with aperiod of 200 nm and an edge length of 100 nm have been fabricated and used aseffective substrates for surface enhanced Raman spectroscopy (SERS) detectionof rhodamine 6G (R6G) molecules. Numerical calculations confirmed the greatenhancement of electric field near the sharp nanoprism corners, as well as the detrimentaleffect of the chromium adhesion layer on localized surface plasmon resonance.The current method can also be used to fabricate non-equilateral nanoprism andthree-dimensional (3D) nanopyramid arrays, and it can be readily extended to othermetals.