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

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 (0.1 mM). 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.