Papers by Keyword: Nanowire

Abstract: This paper is devoted to production of metallic micro-and nanowires (Cu, Co, Ni and Fe) using commercial track membranes. Specially prepared matrices were also fabricated and used for this purpose. The process of electrodeposition of these metals into the nanosized pores was investigated and found to be non-linear for small pores. The obtained ensembles of nanowires could be used as the effective templates for emission of molecules in mass-spectrometry. Mass-spectra of test peptide (gramicidin deposited on substrate - ensemble of copper nanowires) was obtained and investigated in different conditions.

Abstract: This experiment applied the vapor transport method and the AZO catalyst, and successfully grew ZnO nanowires on silicon substrate. The results showed that the factors such as the position of growth substrate, temperature, temperature rising rate, growth time, gas flow volume, and the proportion of ZnO and carbon composition powder, could decide the quality and characteristics of ZnO nanowire. Optimal conditions for ZnO nanowire growth were: carbon and ZnO powders mixed at a 1:1 weight ratio to serve as the material for growing nanowires, located at a distance of 10 cm from the silicon substrate which already had AZO thin film deposed on it; the growth temperature was set at 1100°C for a continuous duration of 70 minutes; the flow volumes of the nitrogen and oxygen gases within the furnace pipe were 70 and 60 sccm, and the furnace pipe temperature rising rate was 20°C/min. In addition, it was observed by FE-SEM that when the substrate was away from the source material by 10 cm, there was nanowire with the radius of 0.11μm and length of 9.3μm. By X-ray we found the characteristic wave summit of ZnO with lattice parameter a = 0.3249 nm and c = 0.5206 nm, was in fine single crystal structure and the directions were all in (002). In field emission measurements, when the current densities was 0.1μA/cm2, the lower initial electric fields corresponding to it was 0.11 V/μm and had the best field enhancement factor with a value of 1782.

Abstract: A compact and versatile nanomanipulation platform and its dirve-control system are being developed. This nanomanipulation sytem is aimed to handle nanowires (NWs) and fabricate nanostructures by NWs in a Scanning Electron Microscope (SEM). The excellent performance of the compact manipulator developed with corase and fine positioning in one unit has been demonstrated, which shows that the resolution is 8 nm and the steps are from 50 nm to 0.8 μm. For the power supply of the manipulator, a three-output driver is designed with a high-power integrated operational amplifier based on a mixed approach of voltage control and current control. The planar push-and-lift handling of NWs is carried out by the use of two tips to demonstrate the capability of the nanomanipulation sytem inside SEM.

Abstract: Nanostructures materials were prepared from rice husk ash by carbon charcoal assisted. The rice husk ash mixed with coconut shell charcoal and Cu-Sn powder as the source materials. The mixtures materials were heated at 1100 °C under atmosphere of nitrogen with flow rate of 1 L/min. After the temperature was cool down, the prepared products were characterized by the stereo microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). The SEM images showed nanostructures materials such as nanoparticles, nanorods and nanowires. The XRD patterns indentified that the consisted of nanostructures materials were SiO₂-CuO phase.

Abstract: Catalyst-free InP nanowires were grown on Si (100) and Si (111) substrates by metal organic chemical vapor deposition and the morphology, crystal structure, and optical properties of the nanowires are investigated. X-ray diffraction results show two peaks of InP (111) and InP (220) in the spectra. Two more peaks of InP (200) and InP (311) are observed if PH₃ thermal annealing is performed on the sample for 15 minutes after nanowire growth is completed. The InP (220), InP (311), and InP (200) peaks originate from InP crystal formation on top of the nanowires; only the InP (111) peak originates from the InP nanowires. Finally, the temperature dependence of the PL peak positions of InP nanowires grown on Si (100) and InP substrate are measured.

Abstract: SiC nanowires have been synthesized by microwave-vacuum heating method at 1480°C, using silicon powders, silica dioxide powders and artificial graphite as raw materials. SEM, TEM and XRD were employed to investigate the micro-structure of obtained specimens. It was shown that β-SiC can be directly synthesized directly without any catalyst on the basis of the vapor-solid (VS) growth mechanism. The obtained specimens exhibited various morphologies and sizes, due to the differences in the reaction temperatures and the distribution of components in the crucible. Products existed in upper crucible were bright-green and more pure, mainly consisting of nanorods with a diameter of about 150nm and some SiC micro-crystals. At the same time, the surface oxidation phenomenon was not obvious. As to the grey-green products existed in other zone, lots of SiC/SiO₂ coaxial nanowires with a diameter around 20-50 nm (the thickness of SiO₂ surface layer was about 2nm) were successfully obtained. Besides, there also remained some un-reacted graphite and silica dioxide. The excitation light with wavelength of 240nm was used to test the photoluminescence properties of the products. Results showed that both of the SiC nanorods and SiC/SiO₂ coaxial nanowires exhibited a strong broad photoluminescence peak at wavelength of about 390nm, displaying a higher degree of blue-shift in comparison to the reported luminescence results of β-SiC nanomaterials.

Abstract: The spark of aggressive scaling of transistors was started after the Moors law on prediction of device dimensions. Recently, among the several types of transistors, junctionless transistors were considered as one of the promising alternative for new generation of nanotransistors. In this work, we investigate the pinch-off effect in double gate and single gate junctionless lateral gate transistors. The transistors are fabricated on lightly doped (10¹⁵) p-type Silicon-on-insulator wafer by using an atomic force microscopy nanolithography technique. The transistors are normally on state devices and working in depletion mode. The behavior of the devices confirms the normal behavior of the junctionless transistors. The pinch-off effect appears at V_G +2.0 V and V_G +2.5 V for fabricated double gate and single structure, respectively. On state current is in the order of 10^-9 (A) for both structures due to low doping concentration. The single gate and double gate devices exhibit an I_on/Io_ff of approximately 10⁵ and 10⁶, respectively.

Abstract: Composite of TiO₂ nanowire and Cu₂O nanocube has been prepared. TiO₂ nanowire with ~240nm in thickness and 20 nm in length were synthesized by using liquid phase deposition(LPD) method at 50°C for 4h on ITO substrate. The anatase phase of TiO₂ nanowire was obtained by annealing the samples at 400°C for 1hin air. The Cu₂O nanocubes were prepared by the reduction of Cu²⁺ions with ascorbic acid in the present of trisodium citrate and sodium dodecilsulfat (SDS) surfactant under an alkaline condition. The SDS addition was added with various concentrations namely 10 mM, 18 mM, and 26 mM during the Cu₂O preparation for spin-coated onto TiO₂ nanowire at 3000 rpm for 30s. An optical property of TiO₂ Nanowire - Cu₂O Nanocube has been characterized by UV-Vis spectroscopy.The original TiO₂ nanowire has single absorption peak at 318 nm, but it was shifted to 321 nm as Cu₂O/SDS addition. A new peak at 440 nm was as the Cu₂O nanocube absorption spectra. The Cu₂O nanocube addition to the TiO₂ nanostructure film caused increase in the optical absorption of the system in the region 400 – 800 nm. We also studied the absorption properties of the hybrid system when Cu₂O nanocube preparation under SDS condition. It was that found the increase in the SDS concentration has caused the optical absorption of the hybrid in this region decreased. This is believed due to the decrease of Cu₂O nanocube size as the SDS concentration increase. This could be due to change in the TiO₂ nanowire-Cu₂O nanocube hybrid-structure. This cooperate may find use in photoelectrochemical application.

Abstract: A comparative study on off-state breakdown characteristics in nanowire JL and IM multiple gate MOSFETs has been performed for different gate bias voltages and fin widths. In order to understand the drain breakdown mechanism with different transistor structures, the device was simulated using the 3-dimensional ATLAS software. The band-to-band tunneling current and the gate-induced-drain-leakage current trigger the off-state breakdown in JL transistor and IM transistor, respectively. From experiment and simulation, the off-state breakdown voltage is lower in JL transistor than in IM transistor. As the gate is biased more negatively, the off-state breakdown voltages are increased in JL and IM transistors.

Abstract: One of the key technologies in future optoelectronics is control of excitons in oxide materials by the coupling with plasmons on noble metal surfaces. Optical properties of ZnO nanowires decorated with Au nanoparticles were studied to understand fundamental mechanism of the coupling and to develop optoelectronic devices with new functionalities. Light intensity at the main peak position in the photoluminescence (PL) spectra of ZnO nanowires was enhanced with the coverage of Au nanoparticles. Lifetime of excitons excited optically decreased by the decoration of Au nanoparticles. Understanding of the coupling between excitons and plasmons leads to optical control of excitons and will pave the way for new type of optoelectronic devices.