We report a novel method for the fabrication of silver nanowires under controlled conditions. Silver nanoparticles were synthesized using a surfactant of octanoic acid via a reverse micelle technique. Hollow nanotubes were prepared under various controlled conditions through self-assembly of surfactant clusters of reversed micelles containing silver nanoparticles. These organized nanotubes were used as a structure-directing template for the preparation of silver nanowires. This is a bottom-up technique for the fabrication of silver nanowires. Self-assembled nanotube construction and the cross section of the nanotubes were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. From the results, reasonable schematic representations of the formation of self-assembled nanoparticles and nanowires were proposed. Further sintering treatment at 500 degrees C burned away the organic compounds and left silver nanowires. The construction of the nanowires was confirmed using SEM, x-ray diffraction (XRD), and energy dispersive x-ray analysis (EDXA). This paper demonstrates that silver nanowires can be fabricated via self-assembled nanoparticles at a controlled low temperature.

Stoichiometric /3-SiC thin films with a high preferred orientation of (111) planes were successfully deposited on Si(100) substrates at a relatively low temperature of 1050 °C from the mixture of methyltrichlorosilane (CH 3 SiCl 3 or MTS) and H 2 in a hot wall LPCVD reactor. No etching of the Si substrate and smooth topography of the deposit were observed at high H 2 /MTS ratios and/or low deposition pressures. The presences of excess silicon, excess carbon, or incorporated hydrogen atoms in the films were not detected. Poor topography, degradation in preferred orientation, and etching of the Si substrate were observed at high values of deposition pressure, MTS concentration, and temperature. The etching on the Si substrate was due to the out-diffusion of Si atoms from the substrate and the presence of Cl-containing radicals resulting from the decomposition of MTS molecules while transporting to the Si substrates. A deposition mechanism was proposed to model the deposition of SiC in a hot wall reactor by using (1) gas phase decomposition of MTS molecules, (2) adsorption of the intermediates on the surface, and (3) reaction of the adsorbed intermediates to form SiC. The deposition rates were predicted very well for various deposition conditions in a hot wall LPCVD reactor.

The kinetics of silicon carbide (SiC) deposition, in a hot-wall chemical vapor deposition (CVD) reactor, were modeled by analyzing our own deposition rate data as well as reported results. In contrast to the previous attempts which used only the first order lumped reaction scheme, the present model incorporates both homogeneous gas phase and heterogeneous surface reactions. The SiC deposition process was modeled using the following reactions: (i) gas phase decomposition of methyltrichlorosilane (MTS) molecules into two major intermediates, one containing silicon and the other containing carbon, (ii) adsorption of the intermediates onto the surface sites of the growing film, and (iii) reaction of the adsorbed intermediates to form silicon carbide. The equilibrium constant for the gas phase decomposition process was divided into the forward and backward reaction constants as 2.0 × 1025 exp[(448.2 kJ/mol)/RT] and 1.1 × 1032 exp[(-416.2 kJ/mol)/RT], respectively. Equilibrium constants for the surface adsorption reactions of silicon-carrying and carbon-carrying intermediates are 0.5 × 1011 exp[(-21.6 kJ/mol)/RT] and 7.1 × 109 exp[(-33.1 kJ/mol)/RT], while the rate constant for the surface reaction of the intermediates is 4.6 × 105 exp[(-265.1 kJ/mol)/RT].

Epitaxial β-SiC thin films were grown on modified Si(100) substrates from methyltrichlorosilane (CH3SiCl3 or MTS) in a hot wall reactor by using low pressure chemical vapor deposition (LPCVD). At 1150 °C, the growth rate of the β-SiC films was 120 Å/min. Epitaxial β-SiC(100) thin films were deposited after the deposition time of 12.5 min. However, the crystallinity of the deposited films was influenced by the deposition time. For example, the occurrence of rotational β-SiC(100) crystals and polycrystalline β-SiC with a highly preferred orientation of (100) planes was obtained for the deposition time of 50 min. XRD and TEM showed the appearance of polycrystalline β-SiC films with a preferred orientation of β-SiC(111) after further increasing the deposition times (time ≥ 75 min). At 1100 °C, polycrystalline β-SiC films with poor surface morphology were observed even though the film had a preferred orientation of β-SiC(100) for short deposition time (e.g., 12.5 min). Polycrystalline β-SiC(111) film was obtained for the deposition time of 200 min at this temperature.

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