| Summary: | 碩士 === 國立新竹教育大學 === 應用科學系碩士班 === 98 === Abstract
Fabrication and properties of one-dimensional nanorods (NRs) were studied in this research. At first, the ZnO NRs were fabricated via vapor-liquid-solid (VLS) mechanism. The influence of the sizes of catalyst on the growth of ZnO NRs would be discussed. Secondly, without VLS mechanism ZnO NRs have been successfully synthesized on m-plane sapphire and c-plane sapphire substrates.
The Au-coated Si substrates and zinc powders were placed inside a furnace for growth of ZnO nanostructures. We got several different nanostructures, such as nanorods, needle-like rods, nanoribbons, nanocombs and nanowalls. The length of nanorods can be controlled. By the method of pre-annealing Au-coated Si substrates, the sizes of Au clusters become larger and the density had been decreased. We discussed the correlation between the diameter of ZnO NRs and the size, position of catalyst metal. Vertically well-aligned ZnO NRs were grown on m-plane sapphire and c-plane sapphire substrates. Compare with the lattice mismatch effect, the VLS mechanism was the main factor to affect the growth of ZnO NRs. The X-ray pattern showed only the (002) reflection peak of ZnO NRs. From the PL spectra measured at room temperature, a strong peak of the near band edge emission and also a very weak green emission associated with defects were observed. The m-plane sapphire substrate grown ZnO film by ALD and coated Au catalyst got nanocombs, lateral-rods and nanoribbons after the growth of the furnace.
Moreover, ZnO NRs were synthesized on sapphire substrates without VLS mechanism. The unique growth directions of NRs have been observed on m-plane sapphire and c-plane sapphire substrates. There were two distinct sets of NRs on m-plane sapphire: some of them pointed to the right and some of them pointed to the left off the substrate plane. The two sets of NRs had different growth rate. Except to those two sets, the third kind of distinct set of NRs, perpendicular to the substrate, was found on c-plane sapphire substrates. The X-ray diffraction pattern showed (100), (002), (103) peaks when NRs were deposited on m-plane sapphire and (002), (101) peaks of NRs were found with c-plane sapphire without catalyst metal. The photoluminescence intensity of NRs growth without catalyst showed 2~3 times higher than catalyst method. The m-plane sapphire substrate grown ZnO film by ALD without coated Au catalyst got ZnO nanograss after the growth of the furnace.
The ZnO nanostructures can be got through change the growth conditions. Fabricated NRs with catalyst showed highly preferred (002) orientation via VLS mechanism no matter what kind of substrates, such as Si(100), m-plane sapphire and c-plane sapphire substrates. ZnO NRs have been successfully grown on sapphire without VLS mechanism by modulated growth processes and showed better PL efficiency.
|
|---|
