| Summary: | 碩士 === 國立臺灣科技大學 === 材料科技研究所 === 93 === Via the technique of vertical-flow cold-wall metal-organic chemical vapor deposition (MOCVD) using highly volatile (MeCp)(COD)Ir as the CVD precursor, self-assembled one-dimensional (1D) iridium dioxide (IrO2) nanocrystals, including nanorods (NRs) and nanotubes (NTs), as well as thin films have been successfully deposited on various substrates. A detailed characterization focusing on the morphology, structures, orientations, and compositions of the various IrO2 samples have been carried out by means of field-emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), and Raman scattering. From a systematic study, we observed the morphological evolution from triangular/wedged NRs, via incomplete/scrolled NTs to hollow square NTs and solid square NRs by precisely controlling the growth rate of these 1D nanocrystals. The results show that the polycrystalline films composed of continuous 3D grains belong to the most stable form as compared to the these 1D nanocrystals. The morphology diagram based on the growth kinetics is given and the possible mechanism of the formation of nanorods and nanotubes has been discussed. The XRD patterns of these various IrO2 1D nanostructures and thin film show the nearly single-crystalline quality and the same [001] long-axis direction. The micro-Raman spectra show there are different residual stress for these various IrO2 nanocrystal. The Raman results for IrO2 grown on different substrates can also prove the lattice mismatch existing between the interface influence the growth of 1D nanostructures very well. Besides, the residual stress can be reduced by annealing treatment or the IrO2 buffer layer.
|
|---|
