Promising Substrates for Surface-Enhanced Raman Spectroscopy

The goal of this study was to fabricate and characterize metal thin films of silver and aluminum to determine the effects of deposition thickness and deposition temperature on nanoparticle morphology and size. Chemical thin films were successfully synthesized by physical vapor deposition (PVD) onto various substrates. Depositions were accomplished by either thermal evaporation or electron beam evaporation. A collimator was implemented that reduced the evaporation spot size of the thermally evaporated copper phthalacyanine (CuPc). Electron beam deposition of silver and aluminum yielded thin films that were confirmed with energy-dispersive X-ray spectrometry and X-ray diffraction. Surface nanostructures were analyzed with scanning electron microscopy (SEM). A trend of increasing density for silver island clusters with increased deposition thickness was noted. Increased nanoparticle size for depositions at elevated temperature was also observed. Similarly, thicker depositions of aluminum yielded larger nanoparticles and a trend of increased nanoparticle size was observed for elevated temperature depositions. Further research to characterize and optimize deposition parameters for surface-enhancement of Raman signals is necessary.