Electrostatic-field-tunable ferroelectric template for photoreduction of silver nanostructures applied in Raman scattering enhancement

Abstract

We present an electrostatic-field-tunable ferroelectric template to produce photoreduced silver nanostructures for Raman scattering enhancement. The intensity and distribution of the surface electrostatic field in the ferroelectric template determine the morphology of the photoreduced silver nanostructures and thus the degree of the Raman signal enhancement. The surface electrostatic field is produced by periodically proton-exchanged (PPE) regions in LiNbO3 and is tuned by thermal annealing to obtain the favorable photoreduced silver nanostructure. The variation of surface electrostatic properties by thermal annealing is simulated using the finite element method and measured by electrostatic force microscopy. The mechanism of silver nanostructure formation affected by the electrostatic field distribution is discussed. The formed silver nanostructures are functionalized by R6G dye to enable Raman signal measurement. The proposed method is demonstrated to be effective in tuning the surface electrostatic field distribution and produces a 4.13 times higher silver nanostructure and a 2.51 times larger Raman intensity in comparison with the conventional PPE sample.