Fig. 4From: Gold Nanohole Array with Sub-1 nm Roughness by Annealing for Sensitivity Enhancement of Extraordinary Optical Transmission BiosensorThe SEM images of the NHAs (a), b before and c, d after annealing with the exposure dose of 40 and 60 fc/dot, respectively. The SEM images show the hole diameter shrank from a 175 nm to c 150 nm (by 13 %) and from b 235 nm to d 209 nm (by 11 %), respectivelyBack to article page