Synthesis of Al–Si nano-template substrates for surface-enhanced Raman scattering application

Abstract

Al–Si nano-porous templates were prepared using filtered cathodic vacuum arc deposition and investigated as surface-enhanced Raman scattering (SERS) active substrates. Al–Si thin films were deposited onto silicon substrates followed by immersion in ammonia solution to remove the aluminium columns to form a nano-porous structure. The pore size and density were controlled mainly by the deposition bias voltage applied to the substrate. Gold particles were deposited onto the nano-porous Al–Si templates by displacement deposition in a solution containing HAuCl4 (0.1mM). The size and dispersion of the deposited Au particles were controlled by the concentration of Au ions, the immersion time and morphology of the Al–Si template. The SERS-activity was measured with Cresyl Violet (C25N3H30Cl) dye as the target molecule, and the enhancement was influenced by the morphology of the nano-porous Al–Si templates. As the pore size decreased a higher density of nucleation sites for the growth of Au nanoparticles was formed resulting in a shorter inter-particle spacing of Au particles, and an enhancement of the Raman signal.