Abstract
In the past decades, nanotechnology has rapidly progressed because enormous possibilities have been unlocked to manipulate materials toward high performance devices. Most works have focused on miniaturizing devices on two-dimensional (2D) surface by thin film technology. In the presented thesis, we adapted a quasi-3D system to reclaim volume from the vertical space and create directive arrangement for materials on 2D surface. The properties of material resident in the nanospace were strongly governed by the vertical and nanoscaled architectures, making the systems dramatically different from their thin film and bulk homologue. In the first part, I introduce a facile route to create crystalline colloidal monolayer (CCM) via air/water interfacial self-assembly, which intrigues researches and engineers by the wafer-scaled nanofabrication without high capital costs. Here, I carefully studied the 2D colloidal system and made efforts to build a diffractive system that can non-invasively monitor the self-assembly process, with nanoscale precision, for batch-to-batch stability. With the assistance of stable and superior self-assembled colloidal array, the desired periodic nanostructure was realized by nanosphere lithography. The second part is the application of CCM derived nanostructured array, related to light management, I use self-aligned nanoring array to enhance the numbers of hot-spots in vertical direction. A high-density-hotpots substrate is highly desirable in practical uses of surface enhanced Raman spectroscope (SERS). Upon locating a nanopillar in each nanowell, a nanohole network, nanoring and nanodisc was formed after gold thin film deposition and producing more edges per unit cell compared to simple nanowell or nanohole structures. Finite-difference time-domain (FDTD) simulations and SERS measurements both confirm that the magnitude of SERS signals can be enhanced compared to simple 2D design. In addition, the developed nanofabrication allowed people to fine tune the geometries of nanostructure, which affect the adsorption spectrum of the substrate. I purposely tune the resonance peaks to fit the incident laser wavelength for each substrate to their optimum condition and further confirmed the enhanced SERS sensitivity is from the enhanced numbers of hot-spots per unit cell.