• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.490.1-490.1
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• 2014

The ZnO nanowire (NW)-based nanogenerators (NGs) can have rectifying current and potential generated by the coupled piezoelectric and semiconducting properties of ZnO by variety of external stimulation such as pushing, bending and stretching. So, ZnO NGs needed to enhance durability for stable properties of NGs. The durability of the metal electrodes used in the typical ZnO nanogenerators(NGs) is unstable for both electrical and mechanical stability. Indium tin oxide (ITO) is used as transparent flexible electrode but because of high cost and limited supply of indium, the fragility and lack of flexibility of ITO layers, alternatives are being sought. It is expected that carbon nanotube and Ag nanowire conductive coatings could be a prospective replacement. In this work, we demonstrated transparent flexible ZnO NGs by using CNT/Ag nanowire hybrid electrode, in which electrical and mechanical stability of top electrode has been improved. We grew vertical type ZnO NW by hydrothermal method and ZnO NW was coated with hybrid silicone coating solution as capping layer to enhance adhesion and durability of ZNW. We coated the CNT/Ag nanowire hybrid electrode by using bar coating system on a capping layer. Power generation of the ZnO NG is measured by using a picoammeter, a oscilloscope and confirmed surface condition with FE-SEM. As a results, the NGs using the CNT/Ag NW hybrid electrode show 75% transparency at wavelength 550 nm and small change of the resistance of the electrode after bending test. It will be discussed the effect of the improved flexibility of top electrode on power generation enhancement of ZnO NGs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.835-840
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• 2011

In this study, a disk-type piezoelectric transformer was fabricated. Its diameter was 50 mm and thickness was 4.5 mm. The driving and generating electrode with their gap of 1mm were fabricated on the top surface. But the common electrode was fabricated on the whole bottom surface. The electrode surface of driving and generating part on the top surface was divided into 2, 4 and 8 pieces. The electrical characteristics with its electrode variation was measured in the range of load resistance of $100{\Omega}{\sim}10_{K\Omega}$. We investigated quantitively the influence of the set-up voltage ratio.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.104-108
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• 2005

We have studied electrode-optic characteristics of IPS (in-plane switching) mode with electrode on top substrate. Because the IPS mode does not have electrode on top substrate. it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems. we have formed additional electrode including dielectric layer in the inner part of the cell and studied electrode-optic characteristics of new IPS cell by changing thickness of dielectric layer.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1035-1039
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• 1999

Ferroelectric properties and reliability characteristics of(111) and (100) preferentially oriented tetragonal Pb(Zr0.2Ti0.8)O3 (PZT) thin film capacitors have been investigated as a function of the top electrode thickness. The (111) preferentially oriented film exhibits 180$^{\circ}$domain switching process with better squareness of hysterisis loop and abrupt change of small singal capacitance-voltage comparing to the (100) preferentially oriented film having 90$^{\circ}$ domain switching process. The domain swithcing process of tetragonal phase PZT is different from that of rhobohedral phase. The film with thinner top electrode shows less initial switching polarization due to less compressive stress but it exhibits better endurance characteristics due to enhancing partial switching region.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1048-1054
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• 1998

The effects of deposition temperature of Pt top electrodes on the electrical properties of Pb(Zr,Ti))$O_3$, (PZT) thin film were investigated. When the Pt top electrodes were deposited at substrate temperatures of $200^{\circ}C$ or above,the ferroelectric properties of the PZT thin film under the Pt electrode were severely degraded. Whereas those of the PZT film where the Pt electrodes were not deposited were not degraded. Water vapors which remained in the vacuum chamber were dissociated into hydrogen atoms by the catalysis of Pt top electrode, and those hydrogen atoms diffused into the PZT film and produced oxygen vacancies at high substrate temperature, resulting in the degradation of the ferroelectric properties of the PZT film located under the Pt electrode. Since the water vapors could not be dissociated into hydrogen atoms without the catalysis of Pt. the degradation of the PZT film did not take place where the Pt electrode were not deposited. The degraded feroelectric properties could be recovered by rapid thermal annealing (RTA) treatment. On the other hand. leakage current characteristics were improved with increasing the deposition temperature of Pt top electrodes.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1499-1501
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• 2003

The A $Sr_{0.7}Bi_{2.6}Ta_2O_9$(SBT)thin films are deposited on Pt-coated electrode(Pt/$TiO_2/SiO_2$/Si) using RF magnetron sputtering method. The electrical properties of SBT capacitors with top electrodes were studied. In the XRD pattern, the SBT thin films in all annealing temperatures had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized at $750^{\circ}C$ and grains largely grew in oxygen annealing atmosphere. The electrical properties of SBT capacitor with top electrodes represents a favorable properties in Pt electrode. The maxim urn remanent polarization and the coercive electric field with Pt electrode are $12.40C/cm^2$and 30kV/cm respectively. The dielectric constant and leakage current density with Pt electrode is 340 and $6.8110^{-10}A/cm^2$ respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.68-68
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• 2010

Electroluminescence (EL) characteristics of green-emission ZnS:Cu,Cl-based ac-type inorganic powder electroluminescent structures were examined by inserting carbon nanotubes (CNTs) into or next to the dielectric layer. For the top-emission type EL structure, where the luminescent light was emitted from the top of the structure, was fabricated by assembling in order, a top electrode, an emitting layer, a dielectric layer, and a bottom electrode from the top. $BaTiO_3$ powder mixed with CNTs was used as a dielectric layer or CNTs were deposited between the bottom electrode and $BaTiO_3$ dielectric layer in order to improve the role of the dielectric layer in the structure. Luminance of an EL structure with CNTs inclusion was greatly enhanced possibly due to the high dielectric constant in the dielectric layer of $BaTiO_3$/CNTs, which is one of hot research topics utilizing nano-objects for intensifying dielectric constant and reducing dielectric loss at the same time. A variation on the CNTs themselves and their inclusion methods in the dielectric layer has been exhorted, and the underlying mechanism for the role of CNTs in the EL structure will be explained in the poster. In order to extend the flexibility of EL devices, EL devices were fabricated on the paper substrate and their performance was compared other EL devices on the plastic-based substrate.

• Journal of Information Display
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• v.7 no.1
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• pp.1-6
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• 2006

A 10" carbon nanotube field emission display device was fabricated with a novel structure with a hopping electron spacer (HES) by screen printing technique. HES plays a role of preventing the broadening of electron beams emitted from carbon nanotubes without electrical discharge during operation. The structure of the novel tetrode is composed of carbon nanotube emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top side of a HES, and an anode. HES contains funnel-shaped holes of which the inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes. They hop along the hole surface to the top extracting electrode. In this study the effects of the addition of HES on emission characteristics of field emission display were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the field emission display panel as a post-treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.81-86
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• 2006

We have studied electrode-optic characteristics of in-plane switching (IPS) of liquid crystal director driven by an oblique electric field. Because the conventional IPS mode does not have an electrode on top substrate, it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems, we have formed additional electrode including dielectric layer in the inner part of the cell on top substrate and studied electrode-optic characteristics of the new device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.94-97
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• 2003

This study uses ZnO thin film as a piezoelectric material and Pt as bottom electrode for FBAR (film bulk acoustic resonator) device. ZnO thin film and Pt were deposited by RF-magnetron sputtering method. ZnO thin film and Pt were oriented to c-axis. Top electrode Al was deposited by thermal evaporation. The membrane was formed of bulk micromachining. The FBAR was evaluated by XRD, SEM and electrical characterization. The resonant frequency was measured by HP 8753C Network Analyzer. A fabricated FBAR device exhibited a resonant frequency of 700 MHz ~ 1.5 GHz. When bottom electrode and top electrode thickness were fixed, the resonant frequency was increased as decreasing ZnO thin film thickness.