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Advanced micro/nanofabrication in one, two, and three dimensions
Advanced micro/nanofabrication of functional materials and structures with various dimensions represents a key research topic in modern nanoscience and technology and becomes critically important for numerous emerging technologies such nanoelectronics, nanophotonics and micro/nanoelectromechanical systems. The goal of this dissertation is to explore non-conventional material processing approaches in fabricating nanomaterials and micro/nanostructures of various dimensions which are challenging to be fabricated via conventional approaches. Research efforts are extended to both laser-based and rapid thermal processing (RTP) techniques for the growth and fabrication of one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) nanomaterials and micro/nanostructures. The following research topics are covered in this dissertation including: 1) laser-assisted chemical vapor deposition (CVD) for highly efficient growth and integration of 1D nanomaterial of carbon nanotubes (CNTs), 2) laser-assisted metal-organic CVD for the growth of GaN thin film and nanowires, 3) wafer-scale growth of graphene sheets on dielectric surfaces via RTP, 4) laser direct writing of graphene ribbons under ambient conditions, and 5) laser direct writing of 3D micro/nanostructures via additive and subtractive processes. Comparing with conventional fabrication methods, the laser-based and RTP-based material processing methods exhibits several unique advantages in the micro/nanofabrication of advanced functional materials and structures. For the 1D nanomaterial growth of CNTs and GaN nanowires, the laser-assisted CVD and MOCVD processes can realize both rapid material synthesis and tight control of growth location and orientation of 1D nanomaterials such as CNTs due to highly intense energy delivery and laser-induced optical near-field effects. For the 2D graphene growth and fabrication, a single-step RTP method was successfully developed for growing high-quality wafer-scale graphene on dielectric surfaces without the post-growth catalyst etching and graphene transfer processes as required in the conventional CVD growth methods. Furthermore, room-temperature and open-air fabrication of large-scale graphene patterns on dielectric surface has been successfully realized by a laser direct writing process. For the 3D micro/nanofabrication, both additive two-photon polymerization (TPP) and subtractive multi-photon polymerization (MPA) were achieved using a femtosecond laser direct writing platform. Furthermore, the combination of additive TPP and subtractive MPA processes enables the fabrication of arbitrary complex 3D micro/nanostructures which are challenging for conventional fabrication methods.
Xiong, Wei, "Advanced micro/nanofabrication in one, two, and three dimensions" (2013). ETD collection for University of Nebraska - Lincoln. AAI3558636.