Fabrication of Ordered 2D Colloidal Crystals on Flat and PatternedSubstrates by Spin Coating

摘要

Spin coating is a simple and rapid method forfabricating ordered monolayer colloidal crystals on flat as wellas patterned substrates. In this article, we show how acombination of factors, particularly concentration of thedispensed colloidal solution (Cn) and spin-coating speed,influences the ordering process. We have performed systematic experiments on different types of substrates with twotypes of colloidal particles (polystyrene and silica). We alsoshow that even when perfect ordering is achieved at somelocations, there might be a significant spatial variation in thedeposit morphology over different areas of the sample. Our experiments reveal that higher Cn is required for obtaining perfectarrays, as the diameter of the colloids (dD) increases. Interestingly, a combination of higher Cn and rotational speed (expressedas revolutions per minute) is required to achieve perfect ordering on a topographically patterned substrate, as compared to thaton a flat surface, because of loss of inertia of the particles during outward flow because of impact on the substrate features.Finally, we also identify the relation between the particle diameter and the height of the pattern features to achieve topographymediated particle ordering.