Abstract
Mo-48.2% Ag films were fabricated by direct current (DC) magnetron sputtering and annealed in an argon atmosphere. The effects of annealing on the surface morphology, resistivity and surface-enhanced Raman scattering (SERS) performance of Mo-48.2% Ag films were investigated. Results show a mass of polyhedral Ag particles grown on the annealed Mo-48.2% Ag films’ surface, which are different from that of as-deposited Mo-Ag film. Moreover, the thickness and the resistivity of Mo-48.2% Ag films gradually decrease as the annealing temperature increases. Furthermore, finite-difference time-domain (FDTD) simulations proved that the re-deposition Ag layer increases the “hot spots” between adjacent Ag nanoparticles, thereby greatly enhancing the local electromagnetic (EM) field. The Ag layer/annealed Mo-48.2% Ag films can identify crystal violet (CV) with concentration lower than 5 × 10−10 M (1 mol/L = 1 M), which indicated that this novel type of particles/films can be applied as ultrasensitive SERS substrates.
Highlights
Surface-enhanced Raman scattering (SERS) is a super-sensitive detection technique [1,2], which has become a powerful spectral method for identification and quantitative analysis of compounds [3].the preparation of high-performance Surface-Enhanced Raman Scattering (SERS) substrate becomes crucial to the practical application of SERS technology due to the weak Raman signal [4,5]
Mo-48.2% Ag films were prepared by a direct current (DC) magnetron sputtering system (JCP-350)
The parameters of crystallites in the films annealed at different temperatures is calculated by the Bragg equation (2d sin θ = kλ) and Scherrer formula D = β0.89λ cos θ
Summary
Surface-enhanced Raman scattering (SERS) is a super-sensitive detection technique [1,2], which has become a powerful spectral method for identification and quantitative analysis of compounds [3]. The preparation of high-performance SERS substrate becomes crucial to the practical application of SERS technology due to the weak Raman signal [4,5]. The performance of SERS depends largely on the surface properties and materials of SERS substrates [6]. SERS substrates are usually made of noble metal (Ag, Au, Cu) nanomaterials, which can excite local surface plasmon resonance (LSPR) to generate strong extinction and scattering spectra [7]. SERS substrates composed of Ag nanostructures exhibit better SERS performance [8]. Various Ag nanostructures, such as nanospheres [9], cubic [10], flower-like [11], triangles [12], nanowires [13], nanoneedles [14], nanorods [15], nanoshells [16], nanoclusters [17]
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