Fabrication of colloidal photonic crystals from submicron-sized spheres

A number of colloidal methods were examined to rapidly fabricate photonic crystals from well-ordered polystyrene (PSt) or silica particles with controlled layers. Using evaporation methods, colloidal solvent was evaporated under a condition to control the deposition of the well-ordered particles on a substrate. However, the time required to produce well-ordered particle arrays was long, with the deposition rates for PSt particles less than 0.02 μm/sec. To increase the deposition rate, the substrates were lined up from the suspensions at a constant speed. Although slow lift up of the substrates resulted in the fabrication of a close-packed structure on the substrates, the number of layers on the substrates was relatively high. A simple dip-coating method proposed by the authors can fabricate close-packed particles in a single layer. Repetition of the dip-coating can fabricate a double-layer of PSt particles on a substrate and a PSt particle mono-layer on a silica particle mono-layer. The fabrication of well-ordered structures shows that the dip-coating is a possible way to rapidly fabricate well-ordered particle arrays with a small number of layers.