(Color online) Schematic illustrations of the spin-coating and selective etching approach for fabricating 2D nanostructures by using colloidal crystal as templates. (a) Arrangement of closely packed PS spheres on a substrate as a template; (b) thinning the template by RIE with oxygen; (c) spin coating liquid materials onto the thinned template formed in (b); (d) solidifying the film formed in (c); (e) etching a thin layer of the film to expose the template; (f) removing the PS template; (c)–(f) cross section views of the processed samples.
(Color online) Field-emission SEM images for samples fabricated by RIE dry etching using mixed CF4 and O2 etchants for step (e) shown in Fig. 1, following the removal of PS spheres by ultrasonic cleaning in toluene. (a) Low magnification, (b) high magnification, and (c) tilted view (45°) images for an etching duration of 5 min. (d) Low magnification, (e) high magnification, and (f) tilted view (45°) images for an etching duration of 7 min. The arrows in (a) indicate the point defects formed during self-assembly of the nanospheres.
(Color online) (a) Perspective view of the sample shown in Fig. 2(d), for which RIE etching using mixed CF4 and O2 etchants was carried out for 7 min at step E shown in Figs. 1(b) and 1(c) show the line scan taken along the directions of mm′ and nn′ as illustrated in (d), (d) top view of AFM image for the same sample. (e) Schematic illustrations of the evolution [cross-section views along the mm′ and nn′ directions, respectively, as shown in (d)] of the hexagonal close-packed silica nanostructure arrays at different etching stages.
Field-emission SEM topographic images for samples where the PS sphere diameters were thinned down by O2 RIE at step B as shown in Fig. 1 The O2 RIE etching durations are (a) 30 s, (b) 50 s, and (c) 70 s, respectively.
(a) Low magnification and (b) high magnification field-emission SEM topographic images of 3D silica nanostructures fabricated through a double layer colloidal crystal template. (c) Field-emission SEM topographic image of 3D silica nanostructures fabricated through a triple layer colloidal crystal template.
(Color online) (a) and (b) show simulated structures that should be obtained through the nanostructure as shown in Figs. 5(a) and 5(c) used as masks. (c) Field-emission SEM topographic image of 2D ordered nanopatterns created on the Si substrate by RIE dry etching through the bilayered 3D silica nanostructures.
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