Development of Surface-Enhanced Raman-scattering Chips Using Highly Oriented Gold Nanoislands Fabricated on MgO(001) Substrates by Pulsed Laser Deposition

We fabricated highly oriented gold nanoislands (HOG-NIs) on a MgO(001) substrate by pulsed laser deposition using an ultra-violet laser (wavelength: 355 nm) to apply them to surface-enhanced Raman scattering (SERS) chips. Gold deposition in argon atmosphere exhibited an Au(111) orientation, while in oxygen atmosphere exhibited an Au(200) orientation. Surface observation of the deposited gold with Au(111) orientation showed that disordered NIs were assembled, while the deposited gold with Au(200) orientation showed that square-shaped NIs formed periodically. To reveal SERS activation properties of the HOG-NIs on MgO(001) substrate, 4-mercaptobenzoic acid (4-MBA) was used as a model analyte. By excitation laser beam (wavelength: 785 nm) irradiation to the 4-MBA-coated SERS chips, SERS signals were observed. From these signals, the enhancement factor was estimated to be over 10
⁷
.