Process Study Of Large-scale Integration Of High-performance One-dimensional Nanostructures For Micro/nano-devices

Recently much attention has been paid to the fabrication of various hierarchical structures that contain both micro-and nano-scale features. Multiscale, hierarchical structures are of potential benefit for the development of various biomimetic, biomedical, micro/nanofluidic, photonic and electronic devices since such structures can enhance structural functionality, device performance and even lead to distinct properties compared to those of individual lengthscale structures. Therefore, much research has been performed to engineer multiscale hierarchical structures based on various approaches. However, the pre-existing approaches possess several obstacles such as low-efficiency, high-cost, requiring expensive equipment and the problem of multi procedures’coupling. In this regard, novel micro/nano integration process with large scale and high controllability is in urgent demand for the development of efficient and reliable nano-devices.In this thesis, several univeral mutli-scale process have been developed to mass-fabricate3-dimentional (3-D) hierachical micro/nanostructures, in an effect to overcome the challenges such as structural coupling design, large-area and low-cost fabrication. In the meanwhile, the evolution mechansim of structure and functionalities under the effect of multi-physical fields have been explored. The proposed study will provide novel strategy for coupling design and integrated process of multi-scale micro/nanostructures. Based on the specific properties of the integrating structures, they are further applied in different devices such as glucose sensor, supercapacitor and light-emitting diode lamp (LED), resulting in improved device-performance. The detailed contents are listed as follows:1. Using C-MEMS as the carbon micro-structrue substrate, large-scale and low-cost integrating approaches have been developed to fabricate3-D multi-scale structures, including C-MEMS/SiOxNy NWs, C-MEMS/SiO2NWs and C-MEMS/CNTs. For the prepared C-MEMS/SiOxNy NW and C-MEMS/SiO2NW structures, the growth behevior has been deeply studied to explore the selective growth mechanism, and the influence of different process parameters on the integration structures has been analyzed. The C-MEMS/CNTs fractal structure fabricated via self-assembly effect of nanostructures and interfacial effect during polymer reaction has been tested respect with its electrical properties, indicating superior electric conductivity over C-MEMS. Futhermore, the C-MEMS/CNTs structure was deposited with glucose oxidase to construct glucose sensor, which has shown fast response to glucose with high sensitivity and selectivity.2. Using flexible carbon micro-structure as the substrate, mass-productive process has been proposed to synthesize highly-ordered ZnO NW arrays onto it. Various procedure parameters have been adjusted to explore their influence on the growth of ZnO NWs, such as the type of substrate, the process to form seed layer, growth time and ph value of growth solution. The obtained ZnO NWs have been hydrogenated to get carbon cloth/H-ZnO NWs integrating structure, which demonstrates improved electrical/electrochemical properties and shows considerable potential in the application of glucose sensor. Moreover, MnO2has been deposited on the carbon cloth/ZnO NW integrated structures to fabricate supercapacitors, which shows improved electrochemical properties with high capacitance retention and Coulombic efficiency after8000cycles, indicating that the high-performance3D hybrid micro/nano-structures have promising applications in flexible electronics.3. Large quantities of SiOxNyNWs and SiO2NWs have been synthesized through the similar method introduced above, and these silicon-based nanowires have been further assembled into micro-scale polymer membranes applied as coating material over reflector cup surface for LED lighting. The SiOxNy NW/micro membrane integrating structure inherits strong diffusive reflection property of SiOxNy NWs over the whole visible wavelength, with more than80%of light reflected at the wavelength range from400to780nm, and thus it has been applied in white LED, showing enhanced lighting efficiency and light distribution. While the SiO2NW integrating structure possesses highly diffusive reflectivity over the UV range, with the maximum up to88%at350nm, which is further applied in UV-LED to greatly improve the light distribution.