High quality BaWO4 nanowire bundles have been synthesized in toluene-sodium dodecylbenzene sulphonate (SDBS)-small amount PEG20000-H2O reverse micelle system. XRD result shows that the obtained BaWO4 belongs to tetrag...High quality BaWO4 nanowire bundles have been synthesized in toluene-sodium dodecylbenzene sulphonate (SDBS)-small amount PEG20000-H2O reverse micelle system. XRD result shows that the obtained BaWO4 belongs to tetragonal phase with scheelite structure. TEM results demonstrate that the obtained BaWO4 nanowire bundles have high aspect-ratio (>650). The experimental results confirm that PEG20000 plays a key role for the formation of BaWO4 nanowire bundles. Other factors which influence the morphology and crystallinity of the product are also briefly discussed. Moreover, the obtained BaWO4 nanowire bundles exhibit strong photoluminescence centered at 397.3 nm with λex=343.5 nm at room temperature, which is different from the bulk BaWO4 crystals.展开更多
In situ synchrotron X-ray diffraction experiments of SWCNT （single-walled carbon nanotube） electrode in alkali halide aqueous electrolyte at several applied potentials were performed, and the change in the diffracti...In situ synchrotron X-ray diffraction experiments of SWCNT （single-walled carbon nanotube） electrode in alkali halide aqueous electrolyte at several applied potentials were performed, and the change in the diffraction pattern of SWCNTs was observed. It was found that the position of the 100 diffraction peak does not change with applied potential while the peak intensity decreases with anion adsorption. It was concluded that the space inside the tube would be the important ion adsorption site for the well-gown SWCNT bundles.展开更多
In this paper, we report a method to change the threshold voltage of SnO2 and In2O3 nanowire transistors by Ga^＋ ion irradiation. Unlike the results in earlier reports, the threshold voltages of SnO2 and In2O3 nanowi...In this paper, we report a method to change the threshold voltage of SnO2 and In2O3 nanowire transistors by Ga^＋ ion irradiation. Unlike the results in earlier reports, the threshold voltages of SnO2 and In2O3 nanowire field-effect transistors （FETs） shift in the negative gate voltage direction after Ga^＋ ion irradiation. Smaller threshold voltages, achieved by Ga^＋ ion irradiation, are required for high-performance and low-voltage operation. The threshold voltage shift can be attributed to the degradation of surface defects caused by Ga＋ ion irradiation. After irradiation, the current on/off ratio declines slightly, but is still close to -106. The results indicate that Ga^＋ ion beam irradiation plays a vital role in improving the performance of oxide nanowire FETs.展开更多
We investigate the charge transport in close-packed ultra-narrow （1.5 nm diameter） gold nanowires stabilized by oleylamine ligands. We give evidence of charging effects in the weakly coupled one-dimensional （1D） n...We investigate the charge transport in close-packed ultra-narrow （1.5 nm diameter） gold nanowires stabilized by oleylamine ligands. We give evidence of charging effects in the weakly coupled one-dimensional （1D） nanowires, monitored by the temperature and the bias voltage. At low temperature, in the Coulomb blockade regime, the current flow reveals an original cooperative multi-hopping process between 1D-segments of Au-NWs, minimising the charging energy cost. Above the Coulomb blockade threshold voltage and at high temperature, the charge transport evolves into a sequential tunneling regime between the nearest- nanowires. Our analysis shows that the effective length of the Au-NWs inside the bundle is similar to the 1D localisation length of the electronic wave function （of the order of 120 nm _＋ 20 nm）, but almost two orders of magnitude larger than the diameter of the nanowire. This result confirms the high structural quality of the Au-NW segments.展开更多
The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-...The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.展开更多
文摘High quality BaWO4 nanowire bundles have been synthesized in toluene-sodium dodecylbenzene sulphonate (SDBS)-small amount PEG20000-H2O reverse micelle system. XRD result shows that the obtained BaWO4 belongs to tetragonal phase with scheelite structure. TEM results demonstrate that the obtained BaWO4 nanowire bundles have high aspect-ratio (>650). The experimental results confirm that PEG20000 plays a key role for the formation of BaWO4 nanowire bundles. Other factors which influence the morphology and crystallinity of the product are also briefly discussed. Moreover, the obtained BaWO4 nanowire bundles exhibit strong photoluminescence centered at 397.3 nm with λex=343.5 nm at room temperature, which is different from the bulk BaWO4 crystals.
文摘In situ synchrotron X-ray diffraction experiments of SWCNT （single-walled carbon nanotube） electrode in alkali halide aqueous electrolyte at several applied potentials were performed, and the change in the diffraction pattern of SWCNTs was observed. It was found that the position of the 100 diffraction peak does not change with applied potential while the peak intensity decreases with anion adsorption. It was concluded that the space inside the tube would be the important ion adsorption site for the well-gown SWCNT bundles.
文摘In this paper, we report a method to change the threshold voltage of SnO2 and In2O3 nanowire transistors by Ga^＋ ion irradiation. Unlike the results in earlier reports, the threshold voltages of SnO2 and In2O3 nanowire field-effect transistors （FETs） shift in the negative gate voltage direction after Ga^＋ ion irradiation. Smaller threshold voltages, achieved by Ga^＋ ion irradiation, are required for high-performance and low-voltage operation. The threshold voltage shift can be attributed to the degradation of surface defects caused by Ga＋ ion irradiation. After irradiation, the current on/off ratio declines slightly, but is still close to -106. The results indicate that Ga^＋ ion beam irradiation plays a vital role in improving the performance of oxide nanowire FETs.
文摘We investigate the charge transport in close-packed ultra-narrow （1.5 nm diameter） gold nanowires stabilized by oleylamine ligands. We give evidence of charging effects in the weakly coupled one-dimensional （1D） nanowires, monitored by the temperature and the bias voltage. At low temperature, in the Coulomb blockade regime, the current flow reveals an original cooperative multi-hopping process between 1D-segments of Au-NWs, minimising the charging energy cost. Above the Coulomb blockade threshold voltage and at high temperature, the charge transport evolves into a sequential tunneling regime between the nearest- nanowires. Our analysis shows that the effective length of the Au-NWs inside the bundle is similar to the 1D localisation length of the electronic wave function （of the order of 120 nm _＋ 20 nm）, but almost two orders of magnitude larger than the diameter of the nanowire. This result confirms the high structural quality of the Au-NW segments.
基金supported by the National Basic Research Program of China(2011CBA02)the National Natural Science Foundation of China(61471189,11227904 and 61101012)
文摘The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.
