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LASER SHOCK IMPRINTING OF METALLIC MEMBRANES TOWARD SOFT TEMPLATES AND ITS APPLICATIONS
Laser shock imprinting (LSI) is a novel fabrication technique capable of manufacturing various membrane materials. This top-down imprinting process can fabricate membranes in high precision, high throughput, and large scalability. It reveals a variety of applications ranging from electronics to photonics, which is beneficial from its reliable and precise modulation of micro/nanostructures.
In this thesis, we firstly proposed and developed a cost-effective LSI process to manufacture hierarchical micro/nanostructured power generators. By combining the conventional soft lithography technique, LSI is well compatible with it to fabricate metal membranes towards soft templates. It is a significant progress from the originally-developed silicon wafer template layout because it effectively reduces the process cost by replacing sophisticatedly developed silicon wafers with low-cost photocurable polymers. In addition, the use of polymer expands the boundary limit of geometrical complexity from simple patterns to hierarchical structures, as a result, we successfully conducted LSI technology to fabricate biomimic leaf structures into metallic membranes with the help of soft SU-8 templates. These fabricated metallic membraned are used as water-driven triboelectric nanogenerators. In addition to the introduction of polymer template, we further developed a successive laser shock imprinting (SLSI) process to fabricate hierarchical nanostructures in a higher resolution. Typically, grating templates are collected via recycling blank discs and used as soft templates. Then multiple times of LSI process are conducted to manufacture membranes into complex nanostructures. The use of blank disc further reduces cost and increase process resolution. The highlight of this part of work is to feature the introduction of metallic thin films on disc template, which plays a significant role during this high strain rate imprinting process. Then, the imprinting mechanism was investigated through the finite element method to validate the experimental findings. Lastly, this soft template LSI process was applied to fabricate low dimensional materials such as nanowires (1D) and nanomembranes (2D), potentially introducing homogeneous and inhomogeneous strain field. Kelvin probe force microscopy was used to directly probe strain-induced changes. This soft-template LSI process reveals a new route of precisely fabricating low dimensional membranes into nanoelectronics systems.