報告人: Dee Chang Fu
報告題目：Growth of Nanostructures, Characterizations and Their Applications
Silicon nanowires (SiNWs) synthesized by hot-wire assisted plasma enhanced chemical vapor (HWCVD) deposition method has been developed and studied. For HWCVD, heated tungsten filament acts to catalytically decompose source and precursor gases (silane and hydrogen) . Due to its high hydrogen decomposition rate, the grown SiNWs typically show high crystallinity compared to other compatible techniques like plasma-enhanced chemical vapor deposition. The utilization of indium compared to the conventional noble metal (gold, copper etc.) as catalyst seed allow the growth of SiNWs at relatively low temperature owing to its low melting temperature (157oC). After the characterization of SiNWs, zinc oxide and tungsten oxide nanowire branches were then separately grown on the SiNWs for field emission, photocurrent and sensing studies.
Bismuth telluride (Bi2Te3) as a phase change material has been explored for its sensing capability. It was synthesized in the form of nanowire and functionalized with palladium nanoparticles (NPs) and used as duo-functioning device - H2 gas sensor and logic devices. Its phase changing behavior (“ON”/crystalline and “OFF”/amorphous states) under certain applied voltage provided the function as logic device. At the same time, it also acted as a hydrogen (H2) sensor at its ON”/crystalline and “OFF”/amorphous states. The palladium NPs functionalization has provided a duo-functioning device (logic and sensing components) in one body.
For the other study, different sizes of Au nanoparticles were deposited on the strontium titanate (STO) substrate. It was found that smaller Au NP sizes have narrowed the band gap and could subsequently increase the visible light absorption and photoactivity. In the last part, cobalt oxide (Co3O4), copper oxide (CuO), Nickel oxide (NiO), palladium oxide (PdO), iron oxide (Fe2O3), indium oxide (In2O3), tin oxide (SnO2) and zinc oxide (ZnO) NWs were prepared by using anodic aluminum oxide (AAO) template. They have an average diameter of 50 nm and length of 10 μm and were aligned separately on interdigitated electrodes on a sensing array module. The sensing behavior was tested using 4 type of gases namely H2, butane (C4H10), carbon monoxide (CO) and nitrous oxide (NO). Sensitivity, stability, and selectivity of the sensing array were studied. Every type of metal oxide NW reacted differently under different gases. The different magnitudes of sensitivity for each type of metal oxide NW to different reactant in a sensing module which consisting of 8 sensing clusters would give a pattern that could potentially function as an electronic nose.