Epitaxial Aluminum Surface-Enhanced Raman Spectroscopy Substrates for Large-Scale 2D Material Characterization
Soniya S. Raja, Chang‐Wei Cheng, Yungang Sang, Chun‐An Chen, Xinquan Zhang, Abhishek Dubey, Ta‐Jen Yen, Yu‐Ming Chang, Yi‐Hsien Lee, Shangjr Gwo
Abstract
Surface-enhanced Raman spectroscopy (SERS) is an ultrasensitive technique to identify vibrational fingerprints of trace analytes. However, present SERS techniques suffer from the lack of uniform, reproducible, and stable substrates to control the plasmonic hotspots in a wide spectral range. Here, we report the promising application of epitaxial aluminum films as a scalable plasmonic platform for SERS applications. To assess the uniformity of aluminum substrates, atomically thin transition metal dichalcogenide monolayers are used as the benchmark analyte due to their inherent two-dimensional homogeneity. Besides the distinctive spectral capability of aluminum in the ultraviolet (325 nm), we demonstrate that the aluminum substrates can even perform comparably with the silver counterparts made from single-crystalline colloidal silver crystals using the same SERS substrate design in the visible range (532 nm). This is unexpected from the prediction solely based on optical dielectric functions and illustrate the superior surface and interface properties of epitaxial aluminum SERS substrates.