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Multiwalled carbon nanotube (MWCNT) arrays were synthesized by thermal chemical vapor deposition. To investigate the effect of O 2 plasma on the properties of the field-emission, MWCNT arrays were exposed to O 2 plasma. Field-emission properties, such as emission current and stability, were greatly improved after the O 2 plasma treatment. The O 2 plasma could remove the entangled thin MWCNTs and etch the tips of MWCNTs, leading to reduced density and sharpened tips. The analytical estimation extracted from the Fowler–Nordheim plot supports the observation of sharpening the tips of nanotubes with little change of the work function of nanotubes.

AC driven inorganic electroluminescence (EL) of the carbon nanotube (CNT)-polymer/phosphor composite was fabricated to investigate the effect of the critical percolation threshold by CNT concentration on EL performance. In order to control the appropriate CNT condition in EL device, CNTs were shortened by cryogenic crushing and purified by thermal treatment. Among various CNT concentrations in the composite film, the critical percolation threshold can be found to be 0.0925 wt.% by fitting conductivity data of the composite film. Near the critical percolation threshold of a CNT concentration, the EL performances of the composite EL were greatly increased compared to the reference EL. The tunneling barrier thickness at the ZnS–CuxS contact could become thin to induce more charge carrier tunneling into ZnS host lattice by the local field enhancement of CNTs, resulting in increased electron–hole recombination to produce more light emission.

The dielectric films consisted of the barium titanate (BaTiO3) powder particle and the polymer were fabricated using the sodium chloride (NaCl)-flux treatment to investigate the effect of the molten salt on the dielectric properties of the BaTiO3 particles. The BaTiO3 particles for the NaCl-flux treatment were prepared by calcining the mixture of the BaTiO3 and the NaCl at the various temperatures. The NaCl-flux treated BaTiO3 particles showed the smooth surface and high crystallinity compared to the non-treated BaTiO3 particles, because the BaTiO3 particles were recrystallized by NaCl-flux treatment. In addition, high dielectric performances of a 20% increase in the dielectric constant, a 40% decrease in the dielectric loss, and a 280% increase in the dielectric strength were achieved. The dielectric films of the NaCl-flux treated BaTiO3 particles could induce the high dielectric performances due to the improvement of the crystallinity with highly packing density.

An alternating current driven electroluminescence (EL) device consisting of a phosphor dispersed in a polymer matrix device was fabricated as a tandem structure. This structure can be formed by duplicating the emitting and conducting layers. The EL device with the tandem structure, particularly the device with the triple emitting layer, was six times brighter than (1460 cd/m 2 at an alternating voltage application of 50 V) the structure with a single emitting layer. This tandem structure plays important roles by increasing the chance of electron–hole tunneling into the phosphor with leading to an increase in brightness by combining the light emitted from several emitting layers in a device. In addition, the adoption of a spin-coating method for the deposition of an emitting layer can allow the production of a dielectric part on the lower-lying emitting phosphor powder particles. The implementation of a dielectric part and emitting part by one spin-coating procedure simplifies the overall fabrication process, particularly for the tandem structure. The significant increase in brightness with each additional emitting layer as well as a facile fabrication process would help to make the EL device a competitive candidate in future displays and lightings.

Alternating-current-type inorganic powder electroluminescence (PEL) devices were successfully fabricated on four kinds of paper substrates, i.e., glossy paper, sticker paper, magazine paper, and newspaper. To protect the paper from wet chemical and heating processes during the formation of the PEL device, the paper substrate was coated with a spin-on-glass layer that served as a buffer layer. In spite of the fragility of paper, quite satisfactory results were obtained-the performance of paper-based PEL devices was almost equivalent to that of PEL devices on a plastic substrate. Extension of a substrate to paper, even to flimsy daily newspaper, will widen the opportunity of PEL devices as one of flexible and disposable displays.

Attaching ZnO nano-structures to specific structures of ZnS has been studied with the aim of introduction the combined benefits of each entity. ZnO nano-structures self-assembled on a wurzite ZnS and ZnS:Cu,Cl (ZC) during thermal treatment owing to the high mobility of the intermediate of zinc oxy–sulfide complex. The growth of ZnO on the surface of ZnS based phosphors is known to reduce the cathodoluminescence (CL) intensity. However, the CL spectra from the ZnO/ZC indicate abnormal enhancement of blue CL emission at 440 nm caused by a secondary excitation of ZC due to the effective transfer of photons generated from ZnO.

An inorganic electroluminescent (EL) device on a flexible polyethylene terephthalate (PET) substrate and its properties were investigated. The transparent conducting film (TCF) made from carbon nanotubes (CNTs) (CNT-TCF) was employed in the flexible EL device. CNT-TCF was formed by filtration of CNT solution and was transferred to the PET film. It was found that the brightness of the inorganic EL device was strongly dependent on the quality of the CNT composite films. After a 3-aminopropyltriethoxysilane treatment of the PET substrate, CNTs uniformly were dispersed and showed a good adhesion to the substrate, and the resulting EL device showed better performance. The flexible EL device showed the brightness of 96.8 cd/m2 at 28 kHz and 50 V.

A cryogenic crushing method to produce short carbon nanotubes (CNTs) is described. Crushing CNTs at liquid nitrogen temperature allows them to be shortened and make them appreciably soluble in a solvent without any dispersant. Typical lengths of less than 500 nm were obtained from 30 min crushing. The CNTs were characterized using atomic force microscopy, thermogravimetric, and Raman analyses.

We report a method to fabricate carbon nanotubes (CNT)/conducting polymer composite films for the application of CNTs to field emission displays. The composite was prepared by a combination of electrochemical polymerization of pyrrole and electrophoretic deposition of CNTs. We obtained a uniform CNT/conducting polypyrrole polymer composite film. The CNTs were mainly coated on protrusions of the polypyrrole film and emitted electrons without rubbing and stretching. We realized a triode-type field emission array (FEA) using the CNT/polypyrrol composite. This FEA showed that the emission current was modulated by gate voltage of 30 V. The film morphology and emission characteristics of the CNT/conducting polymer composite were studied using optical microscopy, scanning electron microscopy, and an emission test in vacuum.

The display characteristics of AC powder electroluminescence (EL) devices were improved by adopting nanomaterials, here single walled carbon nanotubes (CNTs). CNTs were shortened by the cryo-crushing method in order to reduce unnecessary current bypath networks which might be formed by long pristine CNTs. Two approaches utilizing CNTs were investigated—a CNT layer was inserted between an emitting layer and a dielectric layer, and CNT-phosphor composite was used as an emitting layer. Both methods improved the brightness and current density of EL devices (20% brighter and 10% less current density than the reference device). This might be caused by the characteristics of nanomaterials, i.e., high local electric field near the end of nanomaterials and high surface to volume ratio.

A series of 26 (Ba1−xSrx)yTiO2+y thin films with 0.22≤y≤1.01 and x

A simple-but-efficient calibration-spur reduction technique is introduced that utilises the digital-and-analogue hybrid return-to-zero (HRZ) method in a current-steering DAC employing a round-robin-fashioned background current-source calibration scheme. A simulation with a 12 b 500 MS/s current-steering DAC showed 9.9 and 7.8 dB improvements in the spur-free dynamic range and signal-to-noise + distortion ratio, respectively, owing to the reduced calibration spur by the proposed HRZ technique.

Field emission properties of CNTs(carbon nanotubes) have been investigated in the various field, such as flat panel display and x-ray sources. Especially, the x-ray tube which fabricated using the CNTs can be operated with low power consumption compare with filament-based x-ray tubes. The cold cathode — CNTs- can be operated at the lower voltage and the electron which coming out from the CNTs can be controlled easilly by focus electrode. And for high emission current, the device should be stable at the high operate voltage. The gate electrode-mesh-type electrode- can be layered by using glass frit and firing process. At this point, the mesh structure can be controlled for the higher adhesion force which is for the emission stability at the high voltage. The glass frit could be act effectively between mesh electrode and insulating layer because of the designed mesh structure.

The triode-typed field emission (FE) devices using carbon nanotube (CNT) emitters for the x-ray application were fabricated. For the stability of the device, the leakage current between cathode and gate, and the emission current to the anode electrode should be controlled. We realized that the thickness of insulating layer-gap distance between cathode and gate- and the space between the gate electrodes-electron path from cathode and anode- should be controlled for the ratio of the current from cathode to anode (Ia) to the current from cathode to gate (Ig). The ratio of Ia to Ig can be represented the device efficiency. The rectangular-mesh electrode and screen printed insulating layer were controlled for Ia/Ig. When the size of gate hole was the 50 by 700 um — the electrode size is 25 by 700 um — and the thickness of insulator layer was 65 um, the maximum ratio of Ia/(Ia+Ig) was 0.63.

We have fabricated fully vacuum-sealed 5 in. diagonal carbon nanotube field-emission displays of a gated structure with reliable electron emission characteristics. Single-walled carbon nanotube tips were implemented into the gate structure using self-aligned backside exposure of photosensitive carbon nanotube paste. An onset gate electrode voltage for emission was about 60 V and the luminance as high as 510 cd/m2 was exhibited under an application of 100 V and 1.5 kV to gate electrode and anode, respectively.

AC inorganic electroluminescence (EL) devices were fabricated using the emitting layer composed of phosphor-single-walled carbon nanotubes (SWCNTs) composite (PSC) to utilize the local field enhancement of SWCNTs. In order to enhance the electric field in an emitting layer with minimized current paths, bare long SWCNTs were shortened by cryogenic crushing method. After electrical aging treatment of the PSC device, partly formed short SWCNT networks in the emitting layer were effectively removed during the electrical aging treatment. High performance of 60% and 43% increase in efficiency and luminance, respectively, was achieved. This PSC device with short SWCNTs could lead to high brightness due to increased electron tunneling into phosphor. The PSC device reveals the importance of high electric field by SWCNTs leading to high EL performance.

We have studied the effect of chlorination on the dielectric performance of a barium titanate (BTO)–polymer film. Functionalization of BTO powder particles with chlorine (Cl) atoms and/or Cl-containing functional groups was achieved by a simple treatment using chlorinated solvents. The chlorinated BTO (Cl-BTO) particles were incorporated into a cyanoethyl-based polymer and the mixture was spin-coated to produce a composite film. The dielectric constant of the composite film with Cl-BTO was as high as 208 at a frequency of 10 Hz, showing a 2.5-fold increase in dielectric constant compared to composites composed of the neat BTO and the cyanoethyl-based polymer at a frequency of 10 Hz. The observed dramatic increase in dielectric constant would be caused by the interfacial polarization due to the p-type doping effect resulting from the presence of strong electronegative Cl atoms. Given a relatively high dielectric constant, composite films with Cl-BTO were further exploited as a dielectric layer in an inorganic electroluminescence (EL) device. The luminance of the EL device with Cl-BTO was 4090 cd m−2 at a frequency of 1 kHz, showing a 2.03-fold increase in luminance compared to that with the untreated BTO. The improved performance of the EL device is attributed to a high dielectric constant of the composite films that allow for efficient charge carrier tunneling into the phosphor and therefore enhanced luminance and efficiency.

The EL performance of the tandem structured phosphor/polymer/SWCNT composite was greatly increased by structural and material effects, which led to increased tunneling charge carriers into phosphor, resulting in improved luminance. The tandem structured composite EL device exhibited a 1570% increase in the luminance compared to the raw phosphor EL device.

Alternating current inorganic powder electroluminescence (EL) devices with a top-emission structure were fabricated on glass substrates to investigate the structural dependence on EL. The EL performance was examined by comparing the top-emission structure with the conventional EL device, i.e., the bottom-emission structure. High performance, such as 50 and 40% increases in efficiency and brightness, respectively, was achieved. This enhanced EL performance was attributed to the structural change in the EL device, leading to reduced optical loss and enhanced electric field applied to the phosphor.

This paper proposes a method to precisely manipulate a microrobot in the pulsatile flow that simulates the flow characteristics of human blood vessels by utilizing the electromagnetic transfer function of a magnetic navigation system (MNS). The frequency response characteristics of the MNS were utilized so that the input voltages in each coil can precisely generate the required time-varying magnetic force of a microrobot. An experiment which successfully anchoring a microrobot in a pulsatile flow was conducted to verify the proposed method.

A compact two-channel MIMO antenna for mobile handheld devices is proposed. The antenna consists of two folded monopoles with a connecting line facing to the feed point and is orthogonally arranged at the edge of a ground plane. This provides polarisation and pattern diversities with excellent isolation characteristic (< −25 dB at fo). The proposed antenna is designed for the 2.4–2.5 GHz, WLAN (802.11n) service band. The apparent diversity gain in the required bandwidth is 9.95 dB.

Electroluminescence(EL) was observed on conventional cathodoluminescent (CL)phosphor with the incorporation of carbon nanotube(CNT) at ambient air. The role of CNT can be understood as enhancing the local electrical field, which allows electron injection to the active center of phosphor at relatively low operating voltages. In this EL device, the brightness of CLphosphor was significantly improved from no light emission in the case of no addition of CNT to 35 cd / m 2 with 1 wt % CNT at 10 kHz of ac 300 V.

A simple secondary-electron-emission (SEE)-based source was fabricated using a carbon-nanotube-dispersed MgO precursor solution. This emission source exhibits a high SEE gain as over 103. In addition, the self-sustaining current was observed even after turning off the primary electron beam, then the emission current could be modulated by a small electric field variation (1.2–2V∕μm). The electron energy spectrum of the self-sustaining emission indicates that the major character of the emission is attributed to the field-enhanced SEE rather than direct field emission.

The ZnS:Cu, Al phosphor has been studied for low voltage excitation field emission devices. To improve the cathodoluminescence (CL) brightness, the phosphor has been synthesized with iodide-type alkaline and alkali-earth metal as fluxes. Cul and AlF 3 were used as an activator and coactivator, respectively. The phosphor has been characterized in comparison with commercially available cathode ray tubes (CRTs) phosphor and conventionally prepared ones Newly synthesized ZnS:Cu. Al phosphor prepared with iodide-type fluxes has shown higher CL brightness than commercially available phosphor and conventionally prepared ones. The phosphor structure has been analyzed using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. From the analysis, the phosphor particles were composed of cubic and hexagonal phases. The cubic phase was much more formed when iodide-type fluxes were used. This cubic phase helps the phosphor to have high brightness at low voltage operations.