Abstract
ABSTRACT PART Ⅰ Si and Silicide Nanostructures The mechanical properties of single Si nanowire has been investigated. These nanowires showed anomalous flexibility and toughness. The strain of the nanowires was calculated and simulated (>1.5%) to be much higher than the bulk value (<0.2%). Under large deformation of the buckling effect, the spring constant was much lower (~10-4) due to the geometry but the elastic modulus of the nanowire would maintain the same value of the bulk elastic modulus. This result clarified the influence of the nano-sized effect. Meanwhile, the heat endurance and electric property of the cobalt silicide nanocable has been measured. The heat endurance of the nanocable was raised up to 900 ℃, which is 500 ℃ more than that of the nanowire. The nanocable shows that the resistivity could be better than the thin film due to the high quality crystallinity and structure. By Si wafer bonding, Si bicrystal can be formed with different kinds of dislocation arrays. One-dimensional dislocation array can be formed by (001)Si and (110), (111)Si wafer bonding. The dislocation array would confine the shape of the nickel nanosilicide when the distance of the dislocation array is relatively short (<10 nm). In the in situ observation in ultrahigh vacuum transmission electron microscope, the stepwise growth of the silicide nanorod was observed for the first time. The presence of the dislocation line (d~3.1nm) would confine the shape of the silicide nanorod. PART Ⅱ In2O3 Nanostructures Two kinds of the In2O3 nanostructures were synthesized for the first time. The position control of the growth of the nanorings was conducted in conjunction with polystyrene spheres. The absorption and emission peak of the nanorings were at 600 and 620 nm in wavelength. The growth of In2O3 nanowires with different zinc doping levels in the vacuum furnace by a vapor transport and condensation method has been conducted. The ultraviolet peak is attributed to the transition of electrons from oxygen vacancy energy level near the electron band edge to the valence band. The green light emission, on the other hand, is ascribed to the radaitve emission between oxygen vacancy and zinc impurity energy levels. Similar tuning by other impurities can be expected and will be beneficial for possible optoelectronic applications. In addition, laterally self-aligned In2O3 nanowire and nanorod arrays on Si substrate were synthesized for the first time. The orientation relationships between the nanowires and the substrates are In2O3(111)[2 ] || Si(001)[110]. The In2O3 nanowire was found to be p-type semiconductor and the electric conductivity of the nanowire was tuned by nitrogen doping by ion implantation.