Hierarchical growth and morphological control of ordered Cu–Au alloy arrays with high surface enhanced Raman scattering activity

Abstract

Low-cost Cu–Au alloy hierarchical structures are fabricated by coelectrodeposition, and the highest SERS activity is obtained when the atom ratio of Cu and Au is about 88 : 12. The effect of morphology of Cu–Au alloys on the SERS performance is investigated, and the corresponding SERS spectra and FDTD results show that multi-branched Cu–Au dendrites exhibit the highest SERS activity for the massive Raman “hot spots”, especially when the dendrites are self-assembled on highly ordered Si pillar substrates. Using the multi-branched Cu–Au alloy arrays, Rhodamine 6G (R6G) with a trace concentration as low as 10⁻¹⁴ M can be detected, and the enhancement factor (EF) is estimated to be about 6 × 10¹⁰.