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Although the use of atmospheric-pressure microwave plasma to synthesize ZnO nanowires addresses various issues associated with conventional synthesis methods, it is difficult to obtain nanowires with controlled diameters and lengths. Herein, we investigated the effects of microwave input power and water vapor on the structure of ZnO nanowires grown using an atmospheric-pressure microwave plasma system. It was found that the aspect ratio of ZnO nanowires could be controlled by adjusting the plasma temperature and the amount of OH radicals. This method successfully produced ZnO nanowires in a structure-controllable manner with a wide range of aspect ratios from 10 to 340. Interestingly, we found that the sensitivity of the ZnO nanowires to UV irradiation was closely related to the morphology. In particular, the ZnO nanowires with high aspect ratios and densities showed excellent sensing characteristics.

We demonstrate the effect of plasma ignition on the growth temperature decrease of single-walled carbon nanotubes (SWNTs) by using a plasma-coupled hybrid chemical-vapor-deposition system. The horizontal reactor is divided into the plasma ignition region and the SWNT synthesis region. The plasma was generated by using an inductively-coupled system and contributed to efficient decomposition of the feedstock gas. The growth temperature for the SWNTs was suppressed to 500 ◦ C at a plasma power of 400 W with a mixture of C2H4 and H2 gases. The result of optical emission spectroscopy showed H2, Hβ, and CH lines with relatively weak intensities favorable for low-temperature growth of SWNTs.

Vertically-aligned carbon nanotubes (VCNTs) are used as electron source in various field emission applications owing to its high aspect ratio, chemical inertness, mechanical strength and electrical conductivity. Here, we demonstrate that surface structure modification along with thin film coating enhances the field emission performance, such as turn-on voltage, emission site density, and stability. In the present study, VCNTs with different heights were grown on silicon wafers by thermal chemical vapor deposition followed by the structure modification of VCNTs using capillarity-driven water vapor condensation. We obtained various surface morphologies by varying the water vapor exposure time and heating temperature. In addition, the structure-modified VCNTs surfaces were coated with W and SiO2 thin films using electron-beam evaporation. It was observed that W-coated VCNTs with modified surface morphology results in the best field emission performance.

A microwave plasma system operated at atmospheric pressure was utilized to not only synthesize ZnO nanostructures from a micro-sized Zn powder, but also dope with nitrogen simultaneously by changing the ratio of O2 and N2 gas mixture. When pure N2 gas was used, ZnO was not produced due to oxygen deficiency. When the ratio of O2 to N2 was 10:90, 20:80, and 50:50 (vol.%), tetrapod-shaped ZnO rods with a diameter of 29.8 and a length of 256.5 nm were synthesized. When only oxygen was used, ZnO nanorods with a diameter of 626.5 and a length of 852.6 nm were primarily synthesized. Furthermore, it was confirmed from Raman and X-ray photoelectron spectroscope (XPS) analyses that the doping concentration of nitrogen increased with the increase of N2 gas proportion to 50, 80, and 90 vol.%. The increase of the absorbance and the luminescence in the visible light region were confirmed by the change of the energy level due to the N-doping on ZnO. The most effective gas mixture ratio of O2 to N2 for synthesis of ZnO nanomaterials and in situ N-doping was confirmed to be 20:80 (vol.%). This work demonstrates the effectiveness of a microwave plasma system at atmospheric pressure which is available for synthesis of ZnO nanomaterials and simultaneous functional doping on it.

Zinc oxide (ZnO) nanomaterials were efficiently synthesized using a microwave plasma torch system at atmospheric pressure. The Zn powder was passed through a microwave plasma region, in which it melted and vaporized. Tetrapod-type ZnO nanomaterials with a diameter of 29.8 &plusmn, 8.0 nm were synthesized using a high-purity O2/N2 mixed gas. In particular, ZnO nanowires with a diameter of 109.5 &plusmn, 8.0 nm and a length of 5&ndash, 6 &mu, m were produced using an inexpensive compressed air as a microwave plasma gas. It was confirmed that the nanowires synthesized using the compressed air showed higher light absorption in the visible region than the tetrapod-type ZnO. In addition, the redshifts in the absorption peak and photoluminescence peak were observed from 370.6 to 375.2 nm and 380 to 390 nm, respectively. The obtained results can be explained by the change of energy levels due to the defects in the ZnO nanowires such as vacancies and interstitials of Zn and oxygen. Finally, we can conclude that cost-effective compressed air is appropriate not only for the synthesis of ZnO nanowire, but also the enlargement of optical absorption and emission range.

We demonstrate the growth of single-walled carbon nanotubes (SWNTs) using ethylene-based chemical vapor deposition (CVD) and ferritin-induced catalytic particles toward growth temperature reduction. We first optimized the gas composition of H₂ and C₂H₄ at 500 and 30 sccm, respectively. On a planar SiO₂ substrate, high density SWNTs were grown at a minimum temperature of 760℃. In the case of growth using nanoporous templates, many suspended SWNTs were also observed from the samples grown at 760℃; low values of I D /I G in the Raman spectra were also obtained. This means that the temperature of 760℃ is sufficient for SWNT growth in ethylene-based CVD and that ethylene is more effective that methane for low temperature growth. Our results provide a recipe for low temperature growth of SWNT; such growth is crucial for SWNT-based applications.

In this study, an investigation for the degradation of p+ to p+ isolation characteristics in a high voltage process with shallow trench isolation was carried out. It could be explained that the degradation phenomenon was caused by carrier injection. In order to improve this, the results of p+ to p+ isolation degradation were determined under different ion implantation conditions and depths and widths of isolation. From these results, it was found that carrier injection mainly occurred at the sidewall of a trench, and the interface trap between Si3N4 and SiO2 was considered to be a dominant factor based on the result of degradation reduction with increasing thickness of sidewall oxide. Consequently, the improvement of the p+ to p+ isolation degradation caused by carrier injection could be achieved by optimizing the dose of a masked lightly doped drain and a field implantation energy.

Purpose: This study was performed to review the results of PFNA (Proximal Femoral Nail Antirotation) for treating unstable femoral intertrochanteric fractures. Materials and Methods: Forty-seven out of 187 hips treated from September 2006 to March 2010 with PFNA for unstable femoral pertrochanteric fractures were enrolled in this study. The mean duration to radiologic bone union, the functional status and the complications were assessed. The Cleveland index, the tip apex distance, the sliding distance of the blade and the change in the neck-shaft angle were also measured. Results: The mean duration to radiologic bone union was 15.8 weeks and 66% of the patients recovered to a premorbid functional status. The average amount of blade sliding was 5.5 mm and the mean change of the neck-shaft angle was varus 4.4。 . There were 2 cases of penetration of the blade tip, 2 cases of impending penetration, one case of posttraumatic osteonecrosis of the femoral head and 2 cases of lateral wall fractures. Conclusion: PFNA would be preferable for unstable femoral intertrochanteric fractures in terms of the short operation time, the rapid ambulatory recovery and the reduced complications. Yet careful handling is required to avoid a grave complication such as head penetration.