AbstractsEngineering

The goal of this work is to develop methods for nanopatterning that are simpler, lower-cost, and more accessible to a broader variety of researchers. This includes improving pattern quality, simplifying processing methods, reducing reliance on expensive equipment, and demonstrating various applications. The work described herein has resulted in two improved processes for nanopatterning based on the material system of gadolinia-doped ceria (GDC) and yttria-stabilized zirconia (YSZ). GDC-YSZ is shown to self-assemble into arrays of “nanoislands” over macroscopic areas. The first process improvement involves making more uniform and larger arrays of islands. In this method, a thin blanket film of GDC is sputtered onto a single-crystal YSZ-substrate. After annealing, a uniform field of nanoislands is found to cover the surface. No cleanroom or photolithography is required. The second process improvement involves applying a powder suspension of GDC to an YSZ substrate followed by annealing. This process also results in large arrays of nanoislands and requires no special sputtering equipment, resulting in an even simpler, more accessible process. Additionally, the powder-based process shows improved island morphology. Based on these nanopatterning processes, several nanoimprint lithography (NIL) techniques are also demonstrated. The GDC-YSZ material has numerous desirable properties for imprinting, including higher strength and greater thermal and chemical stability compared with traditional nanofabrication materials like silicon, glass, or polymers. The nanoisland patterns can be transferred to soft polymeric materials such as polydimethylsiloxane (PDMS), polystyrene (PS), and ethyleneglycolmethacrylate (EGDMA). The nanoisland mold can be used in high-pressure, high-temperature, and solvent-based processes, and is durable enough to be used in industrial replication applications. The mechanisms of island formation are also discussed. The underlying mechanism for island formation must be clearly understood to support optimization and control of the island morphology. Several future experiments are proposed to elucidate the mechanism by which nanoislands form. Changing the composition of the GDC-YSZ system, including addition of trace impurities, is proposed to control morphology and produce novel, complex nanopatterns. Several applications are described that could benefit from low-cost nanopatterning, including DNA dynamics, cell growth, block copolymer nanopatterning, and superhydrophobic surfaces. Preliminary results are included.