Nucleation and Growth of ZnO Nanorods and the Optical Properties

• Main Authors: Kun-Hua Kuo, 郭昆樺
• Other Authors: Tsong-Pyng Perng
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/53665232828626014449

碩士 === 國立清華大學 === 材料科學工程學系 === 93 === ZnO nanowires and nanorods were synthesized via a CVD process in a horizontal tube furnace. This process was initiated from the carbothermal reduction of ZnO by graphite powder. Then ZnO nanowires were grown on substrates via the vapor-liquid-solid (VLS) process. Both (100) silicon and a-plane sapphire were used as a substrate to control the growth orientation of ZnO nanorods. Nanosphere lithography (NSL) and the VLS growth process of ZnO nanorods were combined to fabricate periodic arrays of ZnO nanorod on the substrate. Periodic array of Au particles with a size of 50-100 nm were deposited on the substrate by NSL technique. ZnO nanorods were then grown on the arrays via the VLS process. Microscopic observation on the nucleation and growth of ZnO nanorods grown from the a-plane sapphire substrate was made. Distortion of Au particle arrays and formation of alloy thin film were noticed during the nucleation stage. The compositions of the alloy thin film and the as-prepared ZnO nanowires were identified by the EDX spectra. The crystallinity and growth orientation of the ZnO nanowires were characterized by X-ray diffraction and HRTEM analysis. Photoluminescence (PL) spectra of ZnO nanowires grown at different temperatures were obtained. It reveals that the intensity of UV emission of the specimens largely depends on the density of nanorods. Also, it is demonstrated that the intensity of green emission is significantly influenced by the length of nanowires, presumably related to the defect density in the nanowires.