Surface-enhanced raman scattering from molecules adsorbed on GaAs surfaces

Abstract

We present the observation of surface-enhanced Raman scattering (SERS) from vibrations of molecules adsorbed on a GaAs surface. We used two different SERS activation procedures. One consists of evaporating a silver island film on the semiconductor surface and the other is based on the use of a chemical etching process. The observed SERS spectra of the adsorbed molecules are similar with both SERS activation procedures. We could not detect Raman scattering from surfaces with either the deposited Ag film or the etching procedure because the vibrational spectra of molecules adsorbed on semiconductor surfaces were too weak to be detectable. With both methods there is enhanced Raman scattering from the surface of the semiconductor due to the excitation of surface-plasmon polariton modes introduced by the surface roughness. These results prove that adsorbed species on semiconductor surfaces can be detected by SERS spectroscopy. This is important for the extension of the applicability of Raman spectroscopy, and suggests the possibility of utilizing the SERS effect as a new surface probe of semiconductor surfaces.