Nanostructured silver substrates produced by cluster-assisted gas jet deposition for surface-enhanced Raman spectroscopy

Abstract

The gas jet deposition (GJD) technique is a very promising method for synthesis of nanostructured films allowing fabrication of uniform thin layers over large areas with high growth rates. In this work, thin silver films of various morphology with the thickness in the range 10–50 nm are produced by the GJD method using a supersonic jet of silver vapor with helium as a carrier gas. The film morphology transformation with increasing thickness is shown to occur from individual nanostructures to a continuous film. The jet is investigated by time-of-flight mass spectrometry and small silver clusters in the deposited flow are observed which are supposed to play a key role in the nanostrtucture formation. The GJD-produced films demonstrate excellent uniformity over a ∼100 cm2 deposited area and exhibit remarkable plasmonic properties. The surface-enhancement Raman scattering (SERS) activity of the films to R6G is investigated and the enhancement factor of about 105 is obtained with the detection limit of 10−8 M R6G. The influence of morphology on plasmonic properties of the films is discussed.