Figure 3

Micrometer-range structure around the aperture edges. (top) Photomicrographs of the apertures from the top. (middle) Laser scanning confocal microscopic images around the edge of the apertures. Bird’s-eye view is shown in the inset. (bottom) Height profiles along the dashed line on the images in the middle. (a–c) The micrometer-range structures of the chips A–C. Note that all the samples were prepared following the same procedures as described in Fig. 2.