Fabrication of large-area and highly uniform interlaced silicon grating arrays for high-performance SERS substrates

Abstract

Surface-enhanced Raman spectroscopy (SERS) provides super ability for detecting trace analytes. However, effective plasmonic architectures and optimal fabrication routes for SERS substrates remained to be further revealed in terms of the cost and performance to promote their applications. In this work, mechano-chemical scanning probe lithography (SPL) was developed to fabricate large-area and high-homogeneity interlaced silicon grating arrays that are hardly achieved by conventional lithography towards high-performance SERS substrates. It was found that this route presented excellent ability for fabricating high-quality groove and hillock structures by controlling the mechanically-driven defects and subsequent wet etching, thereby providing unlimited design diversity for optimizing SERS substrates. Upon designing the layout by finite-difference time-domain simulations, optimizing fabricating processes, and investigating involved selective etching mechanism, various grating patterns were controllably manufactured using the mechano-chemical SPL. SERS spectra of malachite green absorbed on interlaced grating substrates demonstrated an impressive sensitivity and excellent reproducibility with relative deviations of up to 4.09 and 6.08% for batch-to-batch substrate and intra-substrate sampling. This study provides a promising route for customizable and cost-effective fabrication of SERS substrates for chemical and biological sensing.