Surface-enhancement Raman spectroscopy (SERS) is a technique to observe analytes such as molecules, polymers, or biological materials at low concentration per surface area by high amplification of the Raman signal [1–3]. Every molecule has its unique Raman spectrum, which makes SERS a powerful tool for detection [4]. SERS effect was discovered by Fleischmann et al. [5]. He reported the first high-quality Raman spectra of pyridine adsorbed on an electrochemically roughened surface of a silver electrode. However, understanding the new phenomena came rather through other researchers. High-enhancement SERS substrate was discovered independently by Craighton et al. [6] and Van Duyne et al. [7] in 1977. In 1980, theoretical explanations of the SERS effect were given by Gersten and Nitzan [8].