| Abstract
| - We report on a novel template-free method for the fabrication of crack-free colloidal crystals by using amodified vertical deposition method. In this method, a colloidal suspension of silica spheres containing asilica precursor (an acidic tetraethyl orthosilicate (TEOS) solution) was used in the vertical deposition fabricationprocess. Hydrolysis of the silica precursor produced silica species, which filled up the voids between theself-assembled silica spheres to avoid the formation of cracks upon drying of the colloidal crystal film. Thesilica in the interstices of the silica beads can be easily removed using hydrofluoric acid vapor, leaving behinda crack-free colloidal crystal film. The amount of the silica precursor solution needed to fabricate crack-freefilm increased with the increasing number of layers of silica spheres. When an excessive amount of the silicaprecursor solution was added in the vertical deposition process of producing silica sphere bilayer, the resultantcolloidal crystal film curled and peeled off from the substrate and a large-area nanobowl array was left on thesubstrate.
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