“…In recent years, the quality of SERS substrates has considerably improved through the fabrication of plasmonic nanostructures, such as bow-tie [14], [15], [16], [17], island films [19], [20], nanowires [21], nanobundles [22], and nanocubes [23]. Plasmonic nanostructures have received particular attention since it would excite SPPs and create strong electromagnetic hot spots as well [24], [25], [26], [27], [28].…”