title: Porous GaN as a template to produce surface-enhanced Raman scattering-active surfaces.
abstract: Surface-enhanced Raman spectroscopy (SERS) substrates have been prepared by depositing Au or Ag on porous GaN (PGaN). The PGaN used as the template for the metal deposition in these studies was generated by a Pt-assisted electroless etching technique. PGaN was chosen as a potential SERS template due to its nanostructured surface and high surface area, two characteristics that are important for SERS substrates. Metal films were deposited either by solution-based electroless deposition or by thermal vacuum evaporation. SERS spectra were recorded at lambda = 752.5 nm for Au films and at lambda = 514.5 nm for Ag films deposited on PGaN. The SERS signal strength across the metal coated PGaN substrates was uniform and was not plagued by "hot" or "cold" spots on the surface, a common problem with other SERS surfaces. The Ag film deposited by electroless deposition had the highest overall SERS response, with an enhancement factor (EF) relative to normal Raman spectroscopy of 10(8). A portion of the increase in EF relative to typical SERS-active substrates can be assigned to the large surface area characteristic of the PGaN-Ag structures, but some of the enhancement is intrinsic and is likely related to the specific morphology of the metal-nanopore composite structure.
authors.affiliation: Department of Chemistry, Beckman Institute for Advanced Science and Technology, and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA.
authors.forename: Todd L
authors.initials: TL
authors.lastname: Williamson
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Guo
authors.forename: Andrew
authors.initials: A
authors.lastname: Zukoski
authors.forename: Aditya
authors.initials: A
authors.lastname: Sood
authors.forename: Diego J
authors.initials: DJ
authors.lastname: Díaz
authors.forename: Paul W
authors.initials: PW
authors.lastname: Bohn