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Kim, Hoonbae,Lee, Jihye,Sohn, Sunyoung,Jung, Donggeun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.5
<P>Flexible organic photovoltaic (OPV) cells have drawn extensive attention due to their light weight, cost efficiency, portability, and so on. However, OPV cells degrade quickly due to organic damage by water vapor or oxygen penetration when the devices are driven in the atmosphere without a passivation layer. In order to prevent damage due to water vapor or oxygen permeation into the devices, passivation layers have been introduced through methods such as sputtering, plasma enhanced chemical vapor deposition, and atomic layer chemical vapor deposition (ALCVD). In this work, the structural and chemical properties of Al2O3 films, deposited via ALCVD at relatively low temperatures of 109 degrees C, 200 degrees C, and 300 degrees C, are analyzed. In our experiment, trimethylaluminum (TMA) and H2O were used as precursors for Al2O3 film deposition via ALCVD. All of the Al2O3 films showed very smooth, featureless surfaces without notable defects. However, we found that the plastic flexible substrate of an OPV device passivated with 300 degrees C deposition temperature was partially bended and melted, indicating that passivation layers for OPV cells on plastic flexible substrates need to be formed at temperatures lower than 300 degrees C. The OPV cells on plastic flexible substrates were passivated by the Al2O3 film deposited at the temperature of 109 degrees C. Thereafter, the photovoltaic properties of passivated OPV cells were investigated as a function of exposure time under the atmosphere.</P>
Kim, Daekyoung,Kim, Hoonbae,Jang, Haegyu,Jung, Donggeun,Chae, Heeyeop American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.7
<P>Ultra low-k dielectric SiCOH films were deposited with decamethylcyclopentasiloxane (DMCPSO, C10H30O5Si5) and cyclohexane (C6H12) precursors by plasma-enhanced chemical vapor deposition at the deposition temperature between 25 and 200 degrees C and their chemical composition and deposition kinetics were investigated in this work. Low dielectric constants of 1.9-2.4 were obtained due to intrinsic nanoscale pores originating from the relatively large ring structure of DMCPSO and to the relatively large fraction of carbon contents in cyclohexane. Three different deposition regions were identified in the temperature range. Deposition rates increased with temperature below 40 degrees C and decreased as temperature increased to 75 degrees C with apparent activation energies of 56 kJ/mol x K at < 40 degrees C, -26 kJ/mol x K at 40-100 degrees C, respectively. In the temperature region of 40-100 degrees C hydrocarbon deposition and decomposition process compete each other and decomposition becomes dominant, which results in apparent negative activation energy. Deposition rates remain relatively unaffected with further increases of temperature above 100 degrees C. FTIR analysis and deposition kinetic analysis showed that hydrocarbon deposition is the major factor determining chemical composition and deposition rate. The hydrocarbon deposition dominates especially at lower temperatures below 40 degrees C and Si-O fraction increases above 40 degrees C. We believe that dielectric constants of low-k films can be controlled by manipulating the fraction of deposited hydrocarbon through temperature control.</P>
Hoonbae Kim,Hyojin Oh,Chaemin Lee,정동근,부진효 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.10
The electrical and mechanical properties of the plasma polymerized low dielectric constant SiCOH films were investigated. The SiCOH films were produced with tetrakis(trimethylsilyloxy)silane and cyclohexane as precursors by using a plasma enhanced chemical vapor deposition. When the deposition plasma powers were changed from 10 to 50 W, the relative dielectric constant of the SiCOH film increased from 2.09 to 2.76 and their hardness and elastic modulus were changed from 1.6 to 5.6 GPa and from 16 to 44 GPa, respectively. After thermal annealing at 500 oC, the annealed SiCOH films showed relative dielectric constants of 1.80-2.97, a hardness of 0.45-0.6 GPa and an elastic modulus of 6-7 GPa. And then, the chemical structures of asdeposited and annealed SiCOH films were analyzed by using Fourier transform infrared spectroscopy.
Kim, Hoonbae,Ban, Wonjin,Kwon, Sungruel,Yong, Sanghyun,Chae, Heeyeop,Jung, Donggeun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.5
<P>Organic electronic devices (OEDs) are quite suitable for use in flexible devices due to their ruggedness and flexibility. A number of researchers have studied the use of OEDs on flexible substrates in transparent, flexible devices in the near future. However, water and oxygen can permeate through the flexible substrates and can reduce the longevity of OEDs made from organic materials, which are weak to moisture and oxygen. In order to prevent the degradation of the OEDs, researchers have applied an encapsulation layer to the flexible substrates. In this study, Al2O3/plasma polymer film/Al2O3 multi-layers were deposited on polyethylene-naphthalate substrates through a combination of atomic layer deposition and plasma-enhanced chemical vapor deposition (PECVD). The plasma polymer film, which is located between the Al2O3 films, is deposited via PECVD with the use of a tetrakis(trimethylsilyloxy) silane precursor. The power of the plasma deposition varied from 10 to 50 W. The hydrophobicity of the plasma polymer film surfaces was investigated by measuring the water contact angle. The chemical structures of the plasma polymer films were measured via ex-situ Fourier transform infrared analysis. The permeation curves of the various films were analyzed by performing a calcium (Ca)-test.</P>
Kim, Hoonbae,Min, Byung-Wook IEEE 2018 IEEE Sensors Journal Vol. No.
<P>For the first time, we analyze the mechanism of electromagnetic interference (EMI) in an advanced in-cell touch (AIT) panel, which is a state-of-the-art in-cell touch screen panel technology. The AIT panel has stronger EMI generation at a specific frequency band (0.15 ~ 30 MHz) due to a load free driving (LFD) method. The LFD is adopted to overcome the structural vulnerability of in-cell touch panel, which incurs large parasitic capacitance due to the touch electrodes within the display panel. In order to overcome the EMI problem, we present a novel driving method using pseudo random pulse (PRP). The power spectrum of PRP is well spread over the frequency band, resulting in a lower EMI. We measured the EMI level with a near-field probe, and the proposed driving method shows the EMI reduction of 6.5 dB. This EMI reduction is accomplished without structural reconfiguration, as well as the touch performance remains the same as that before PRP is applied. Therefore, the proposed driving method can be utilized in the field of automotive, military, and aviation industries as a user interface which requires high touch performance and low EMI generation due to the peculiarities.</P>
Kim, Hoonbae,Yeo, Donghyun,Won, Beomhee,Yu, SeGi,Jung, Donggeun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.5
<P>Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius <= 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed.</P>
Kim, Hoonbae,Oh, Hyojin,Lee, Chaemin,Jung, Donggeun,Boo, Jin-Hyo Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.10
The electrical and mechanical properties of the plasma polymerized low dielectric constant SiCOH films were investigated. The SiCOH films were produced with tetrakis(trimethylsilyloxy)silane and cyclohexane as precursors by using a plasma enhanced chemical vapor deposition. When the deposition plasma powers were changed from 10 to 50 W, the relative dielectric constant of the SiCOH film increased from 2.09 to 2.76 and their hardness and elastic modulus were changed from 1.6 to 5.6 GPa and from 16 to 44 GPa, respectively. After thermal annealing at $500^{\circ}C$, the annealed SiCOH films showed relative dielectric constants of 1.80-2.97, a hardness of 0.45-0.6 GPa and an elastic modulus of 6-7 GPa. And then, the chemical structures of as-deposited and annealed SiCOH films were analyzed by using Fourier transform infrared spectroscopy.