Fig. 2

The SEM images of fabricated NHAs of hole diameter of 150 nm and period of 500 nm through a conventional single liftoff process and b double liftoff process. Three different types of defects were found in conventional liftoff process as marked as region 1) resist pillars covered by lateral deposition of Au, 2) nanoholes with chimney shape, and 3) collapsed pillar. The inset images show the higher magnification of a chimney-shape nanoholes and b nanohole array of period of 500 nm and hole diameter of 150 nm