Changes in Extinction Properties of Gold Nanorod Arrays by Heat Treatment

Abstract

We investigated the changes in shape and extinction intensity of Au nanorod arrays by rapid thermal annealing (RTA). RTA was performed at 400~800°C for 3 min in an N₂ atmosphere using a halogen lamp as a heater. With increasing annealing temperature, the surface roughness of the rod decreases, the long axis of the rod shrinks while the short axis inflates, and finally some rods split. The wavelength and intensity of localized surface plasmon resonance varied with the rods shape. In particular, annealing at 800°C shifts the high-order (3λ/2) mode along the long axis from the near infrared to the visible region. Also surface lattice resonance is observed, showing that the periodicity of the array is retained even after annealing at 800°C.