Jin Ai-Zi

The role of periodicity in enhanced transmission through subwavelength hole arrays

Two kinds of subwavelength hole arrays in metallic films are designed to verify the important role of the periodicity in enhanced transmission of light. The measured optical spectra show that the quasiperiodic hole arrays exhibit an enhanced transmission peak centred at 707 nm with a transmission intensity of about 20%, while no plasmon resonance peak is found for the amorphous hole arrays. When the hole diameter decreases in the quasiperiodic structure, the position of the transmission peak shifts slightly, and the transmittance drops. These phenomena indicate the important role of the long-range structural order (particularly the periodicity) in assisting the coupling of incident light wave with the surface plasmon modes of the metallic structures.

Current-voltage characteristics of individual conducting polymer nanotubes and nanowires

We report the current-voltage (I{V ) characteristics of individual polypyrrole nanotubes and poly(3,4ethylenedioxythiophene) (PEDOT) nanowires in a temperature range from 300 K to 2 K. Considering the complex structures of such quasi-one-dimensional systems with an array of ordered conductive regions separated by disordered barriers, we use the extended ∞uctuation-induced tunneling (FIT) and thermal excitation model (Kaiser expression) to flt the temperature and electric-fleld dependent I{V curves. It is found that the I{V data measured at higher temperatures or higher voltages can be well fltted by the Kaiser expression. However, the low-temperature data around the zero bias clearly deviate from those obtained from this model. The deviation (or zero-bias conductance suppression) could be possibly ascribed to the occurrence of the Coulomb-gap in the density of states near the Femi level and/or the enhancement of electron-electron interaction resulting from nanosize efiects, which have been revealed in the previous studies on low-temperature electronic transport in conducting polymer fllms, pellets and nanostructures. In addition, similar I{V characteristics and deviation are also observed in an isolated K0:27MnO2 nanowire.

Electrical Conductivity and Current–Voltage Characteristics of Individual Conducting Polymer PEDOT Nanowires

We report the current–voltage (I–V) characteristics and electrical conductivity of individual template-synthesized poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires (190 ± 6 nm in diameter and ort = 11.2 ± 2 Ω−1cm-1) over a wide temperature range from 300 to 10K. With lowering temperature, the I – V characteristics become nonlinear around 50K, and a clear Coulomb gap-like structure appears in the differential conductance (dl/dV) spectra. The temperature dependence of the resistance below 70K follows inR ∞ T-1/2, which can be interpreted as Efros–Shklovskii hopping conduction in the presence of a Coulomb gap. In addition, the influences of measurement methods such as the applied bias voltage magnitude, the two-probe and four-probe techniques used in the resistance measurements are also reported and discussed.

The influence of hole shape on enhancing transmission through subwavelength hole arrays

The extraordinary light transmission through a 200-nm thick gold film when passing through different subwavelength hole arrays is observed experimentally. The sample is fabricated by electron beam lithography and reactive ion etching system. A comparison between light transmissions shows that the hole shape changing from rectangular to diamond strongly affects the transmission intensity although both structures possess the same lattice constant of 600 nm. Moreover, the position of the transmission maximum undergoes a spectral red-shift of about 63 nm. Numerical simulations by using a transfer matrix method reproduce the observed transmission spectrum quite well.

Optical properties of the direct-coupled Y-branch filters by using photonic crystal slabs

We fabricated a new type of two-dimensional photonic crystal slab filter. The resonant cavities were directly put into the waveguide arms. The optical transmissions of the filters were measured and the results show that the optimized two-channel filters give good intensity distribution at the output ports of the waveguide. A minimum wavelength spacing of 5 nm of the filter outputs is realized by accurately controlling the size of the resonant cavities.

Electrical conductivity of individual polypyrrole microtube

Conducting microtubes (0.4–0.5μm in outer diameter) made of polypyrrole (PPy) doped with p-toluene sulfonic acid (PTSA) were synthesized by a self-assembly method. We report the electrical conductivity of an individual PPy microtube, on which a pair of platinum micro-leads was fabricated by focused ion beam deposition. The measured room-temperature conductivity of the individual PPy microtube was 0.29S/cm, which is comparable to that of template-synthesized PPy micro/nanotubes. The temperature dependence of conductivity of the individual microtube follows the three-dimensional variable-range hopping (3D VRH) model.

Current--voltage characteristics of an individual helical CdS nanowire rope

This paper studies the electronic transport in an individual helically twisted CdS nanowire rope, on which platinum microleads are attached by focused-ion beam deposition. The current–voltage (I –V) characteristics are nonlinear from 300 down to 60 K. Some step-like structures in the I – V curves and oscillation peaks in the differential conductance (dI/dV - V) curves have been observed even at room temperature. It proposes that the observed behaviour can be attributed to Coulomb-blockade transport in the one-dimensional CdS nanowires with diameters of 6–10 nm.

Fabricating nanofluidic channels and Applying it for single bio-molecule study

In the emerging field of nanobiotechnology, further downsizing the fluidic channels to the nanometer scale is attractive for both fundamental studies and technical applications. The insulation silicon nitride membrane nanofluidic channel array which have width ~75 nm and depth ~100 nm and length 50 mum were created by focused-ion-beam instrument, the lambda-DNA molecules were put inside them and the dynamic characteristics were initial studied, a fluorescence microscopy was used to observe the images. We observed lambda-DNA moved inside the nanotrenches which dealt with activating reagent Brij aqueous solution only by capillary force, this will help us to understand more DNA dynamics characteristics and more information about single biomolecule transporting through a nanopore

A New Bipolar Type Transistor Created Based on Interface Effects of Integrated All Perovskite Oxides

Oxide transistor is the basic device to construct the oxide electronic circuit that is the backing to develop integrated oxide electronics with high efficiency and low power consumption. By growing the perovskite oxide integrated layers and tailoring them to lead semiconducting functions at their interfaces, the development of oxide transistors may be able to perform. We realize a kind of p-i-n type integrated layers consisting of an n-type cuprate superconductor, p-type colossal magnetoresistance manganite, and a ferroelectric barrier (i). From this, bipolar transistors were fabricated at the back-to-back p-i-n junctions, for which the Schottky emission and p-n junction barriers, as well as the ferroelectric polarization, were integrated into the interfaces to control the transport properties; a preliminary but distinct current gain greater than 1.6 at input current of microampers order was observed. These results present a real possibility to date for developing bipolar all perovskite oxide transistors.

Dependence of Morphology of SiOx Nanowires on the Supersaturation of Au-Si Alloy Liquid Droplets Formed on the Au-Coated Si Substrate

A thermodynamic theory about the dependence of morphology of SiOx nanowires on the super-saturation of alloy liquid droplets has been proposed on the basis of the vapour-liquid-solid growth mechanism and has been supported experimentally. By changing the Si concentration in the Au-Si liquid droplets formed on the Au-coated Si substrate, firework-, tulip- and bud-shaped SiOx nanowires were synthesized by a thermal evaporation method and distributed concentrically around some void defects in the Si substrate. Voids were formed underneath the surface of the Si substrate during the thermal evaporation at 850°C and resulted in the Si-concentration deficient thus different saturation of Au-Si droplets. Electron microscopy analysis showed that the nanowires had an amorphous structure and were terminated by Au-Si particles.