Vertically Aligned Silicon Nanowire Array Decorated by Ag or Au Nanoparticles as SERS Substrate for Bio-molecular Detection

This review article summerises preparation techniques of vertically aligned silicon nanowire (Si NW) arrays through metal-assisted chemical etching (MacEtch) process and plasmonic nanoparticles (Ag and Au) with the perspective of the fabrication of surface-enhanced Raman scattering (SERS)-active substrates which are highly efficient for bio-molecular detection. At first, basic methods and mechanisms for SERS have been introduced and size and shape effects of the nanoparticles (NPs) on plasmonic vibration have been discussed. Comparative discussions on optical and plasmonic characteristics of Ag and Au NPs have also been presented in this section. Potential techniques for the synthesis of Ag and Au NPs with different sizes and shapes have been reported in the following section. Basic processes and mechanism for the fabrication of vertically aligned Si NW arrays on Si by MacEtch of Si wafer have been discussed. Template-assisted fabrication techniques for the vertically aligned Si NW arrays with controlled diameter and number density have also been reported. Finally, multifarious ways for the fabrication of SERS-active substrates by assembling noble metal NPs onto the NW surface have been discussed and their performance for bio-molecular detection has also been reported.