Fabrication of long-ranged close-packed monolayer of silica nanospheres by spin coating

In light of the importance of nanostructured surfaces for various technological applications, it becomes imperative to look for simple and reliable methods for assembling ordered nanostructures over a large area. Several methods have been employed for fabricating nanostructured surfaces but not many are compatible with large-scale fabrication. Here we demonstrate the fabrication of long-range ordered close-packed monolayer of silica nanospheres (SNs) (size approximately 200 nm) deposited on a silicon substrate by a three-step spin coating technique in atmospheric conditions, which could be realized on a very small time scale but has significant potential in numerous applications. The dispersity of the SNs and the influence of various deposition parameters like surface modification, SNs concentration, spin speed, spinning time and the volume of aliquot spread over the silicon substrate were studied to optimize uniform high surface coverage of the film. A relatively uniform monolayer film and high surface coverage of silica particles ranging from 85 to 90% were achieved by optimizing the above deposition parameters. These nanostructures templates can be used in the formation non-close-packed monolayer facilitating further development of ordered nanowires, which highlights the prospect of this approach as a simple preparation method for ordered arrays of nanospheres. We conclude that this method is highly suitable for industrial applications, because of faster and effective rate of production and scalability.