Figure 2

Nanofabrication procedures for repeated solid-state dewetting of thin Au film.

(a) the nanofabrication steps of nanogap-rich Au nanoislands on a quartz substrate; (i) an initial thin Au film was thermally evaporated on a quartz glass wafer, (ii) the thin Au film was transformed into Au nanoislands after the first dewetting process, (iii) an additional thin Au film was thermally evaporated over the predetermined Au nanoislands and (iv) subsequently annealed for enlarged Au nanoislands with small gap spacing. (b) SEM and AFM images of Au nanoislands from a single dewetting of 5 nm and 10 nm in initial film thickness and repeated dewetting of thin Au film with 5 nm in both and additional thickness, denoted by t_1Au = 5 nm, t_1Au = 10 nm for a single dewetting process and t_1Au = 5, t_2Au = 5 nm for the repeated dewetting process, respectively. (c) side-view TEM images of Au nanoislands with enlarged view of a single nanoisland. (d) the extracted effective diameters and packing densities of Au nanoislands from SEM images and (e) optical images of nanofabricated 4 inch wafers corresponding to a single and repeated dewetting process. (SEM and AFM image scale bar: 100 nm, TEM images: 50 nm and inset of TEM images: 10 nm).