Using Si and Ge nanostructures as substrates for surface-enhanced Raman scattering based on photoinduced charge transfer mechanism.

The possibility of utilizing the Si and Ge nanostructures to promote surface-enhanced Raman scattering (SERS) is discussed. The vibronic coupling of the conduction band and valence band states of Si or Ge with the excited and ground states of the target molecule during the charge transfer (CT) process could enhance the molecular polarizability tensor. Using H-terminated silicon nanowire (H-SiNW) and germanium nanotube (H-GeNT) arrays as substrates, significant Raman enhancement of the standard probes, Rodamine 6G (R6G), dye (Bu(4)N)(2)[Ru(dcbpyH)(2)-(NCS)(2)] (N719), and 4-aminothiophenol (PATP), are demonstrated. The abundant hydrogen atoms terminated on the surface of SiNW and GeNT arrays play a critical role in promoting efficient CT and enable the SERS effect.