Fabrication of hierarchical nanostructures using binary colloidal nanosphere assembly

Abstract

In this paper, we investigate the self-assembly of hierarchical nanostructures using monodispersed nanospheres with two different diameters. Our approach is to use a two-step method where the assembly of larger 200 nm nanospheres is used to direct the assembly of smaller 50 nm particles. This self-assembly technique is based on Langmuir–Blodgett assembly and has low equipment cost when compared with traditional lithography methods. We examine the effects of substrate surface treatment, solution concentration ratio, and spin speeds on the quality of the hierarchical assembly. The fabricated samples are examined using optical and scanning electron microscopy to investigate assembly yield. Various defect types are identified and mitigated by process control. The ability to create more complex assembly can result in smaller features and can enhance the performance of photonics and nanostructured surfaces.