Formation Regularities of Sers-Active Substrates Based on Silver-Coated Mesoporous Silicon

Abstract

SERS-active substrates have been fabricated by immersion deposition of Ag on mesoporous silicon. The SERS intensity has been found to alter simultaneously to the periodical repacking of Ag particles which grow according to the Volmer-Weber mechanism. We have determined the crucial parameter ("effective time") for managing the SERS signal intensity. "Effective time" has been calculated as a product of the immersion time by the Ag salt concentration.Surface-enhanced Raman scattering (SERS) is a sensitive technique which provides detailed information on the composition of analyzed materials at extremely low concentrations up to individual molecules. Recently, immersion deposition of Ag nanoparticles (NPs) on porous silicon (PS) templates has been found to yield SERS-active substrates of high sensitivity and storage stability [1]. To obtain the maximum enhancement of Raman signal a number of experiments have been performed to optimize the Ag deposition on PS [2-4]. Nevertheless, the mentioned works have not resulted in a systematic study of the SERS signal intensity as a function of Ag deposition regimes. In this paper, we report on the intensity regularities of SERS signal from the analyte molecules adsorbed on the Ag/mesoPS substrates fabricated on n + -type Si. It has been shown that SERS-activity is directly related to the peculiarities of the structure of Ag deposit which can be managed by immersion time (t imm ) and Ag salt concentration (C(AgNO 3 )).Uniform PS layers were formed by anodization of n + -type Czochralski (100) Si wafers in the 1:3:1 mixture of HF, H 2 O and C 3 H 7 OH at 100 mA/cm 2 for 85 s. The diameter and length of pores were 25 nm and 5 m, respectively. The Physics, Chemistry and Applications of Nanostructures Downloaded from www.worldscientific.com by NANYANG TECHNOLOGICAL UNIVERSITY on 08/26/15. For personal use only.