Size correlation of optical and SERS properties for highly ordered Au nanocone arrays with sub-100 nm feature size

Using ultrathin anodic aluminum oxide membranes as evaporation masks, highly ordered Au nanocone arrays with sub-100 nm feature size were fabricated on glass substrates. The size of Au nanocones was adjusted by the easily controllable nanopores' dimension. Influences of Au nanocone size on the optical property and SERS activity were characterized by extinction and Raman spectra, respectively. For one thing, the spectral position of plasmon resonances was seen to slightly blue-shift with increasing the nanocone size, which coincided well with the result of finite-difference-time-domain simulation. For another, glass substrates patterned by Au nanocone arrays exhibited a high surface enhanced Raman scattering sensitivity to Rhodamine 6G. Compared with the bulk sample, the estimated enhancement factor was boosted from 8 x 10(6) to 1.79 x 10(7) as the diameter of Au nanocone increased from 36 to 77 nm. Such highly ordered nanocone arrays with tunable and uniform size have great potential for various optical or spectrographic applications.