Development of a scalable bottom-up nanofabrication platform

This study covers three important research topics related to the application of self-assembly colloidal crystal by spin coating. The first topic describes the antireflection coatings on glass and semiconductor materials. Inspired by nature, the protruding nipples on moth eye can effectively reduce light reflection. Creating sub-300nm features with current lithography-based fabrication techniques (e.g., photolithography or interference lithography) is costly and is limited by either low resolution or small sample size. The spin-coating technology that combines the simplicity and cost benefit of bottom-up self-assembly with the scalability and compatibility of standard top-down microfabrication is used in creating non-close-packed moth eye antireflection coatings.;The second topic describes the templating fabrication of surface enhanced Raman scattering (SERS) active substrates. Wafer-scale metallic pyramid arrays with sharp nanotips can be replicated from silicon templates by a simple adhesive peeling process. The resulting nanopyramid arrays show stable surface enhancements for Raman scattering from benzenethiol molecules adsorbed at the metal surfaces. To further improve the reproducibility, we report a simple colloidal templating approach for fabricating surface-enhanced Raman scattering (SERS) substrates with highly reproducible enhancement over wafer-sized areas. The substrates are produced by evaporating a thin layer of gold on highly ordered silica colloidal crystal-polymer nanocomposites created by a scalable spin-coating technology. The ordered inorganic-organic composite structure induces the formation of island-type gold films. Systematic measurements and statistical analysis show that the substrates exhibit high SERS reproducibility with less than 28% standard deviation over a 4 in. wafer surface. Finite element electromagnetic modeling has also been employed to simulate SERS enhancement from these structured substrates.;The third topic presented is the templated fabrication of sub-100nm nanostructures. Periodic polymer nanoposts and metal nanohole arrays with tunable size have been fabricated by templating from spin-coated two-dimensional non-close-packed colloidal crystal-polymer nanocomposites.