• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.442-449
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• 2006

Electrical, optical, and structural properties of indium zinc oxide (IZO) films grown by a box cathode sputtering (BCS) were investigated as a function of oxygen flow ratio. A sheet resistance of $42.6{\Omega}/{\Box}$, average transmittance above 88% in visible range, and root mean spare roughness of $2.7{\AA}$ were obtained even in the IZO layers grown at room temperature. In addition, it is shown that electrical characteristics of the top-emitting organic light emitting diodes (TOLEDs) with the BCS grown-IZO top cathode layer is better than that of TOLEDs with DC sputter grown IZO top cathode, due to absence of plasma damage effect. Furthermore the effects of oxygen flow ratio in IZO films are investigated, based on x-ray photoelectron spectroscopy (XPS), ultra violet/visible (UV/VIS) spectro-meter, scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis results.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.176-180
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• 2002

During the last two decades the laser beam has progressed from a sophisticated laboratory apparatus to an adaptable and viable industrial tool. Especially, in its welding mode, the laser offers high travel speed, low distortion, and narrow fusion and heat-affected zones (HAZ). The principal obstacle to selection of a laser processing method in production is its relatively high equipment cost and the natural unwillingness of production supervision to try something new until it is thoroughly proven. The major objective of this work is focused on the combined features of gas tungsten arc and a low-power cold laser beam. Although high-power laser beams have been combined with the plasma from a gas tungsten arc (GTA) torch for use in welding as early as 1980, recent work at the Ohio State University has employed a low power laser beam to initiate, direct, and concentrate a gas tungsten arcs. In this work, the laser beam from a 7 watts carbon monoxide laser was combined with electrical discharges from a short-pulsed capacitive discharge GTA welding power supply. When the low power CO laser beam passes through a special composition shielding gas, the CO molecules in the gas absorbs the radiation, and ionizes through a process known as non-equilibrium, vibration-vibration pumping. The resulting laser-induced plasma (LIP) was positioned between various configurations of electrodes. The high-voltage impulse applied to the electrodes forced rapid electrical breakdown between the electrodes. Electrical discharges between tungsten electrodes and aluminum sheet specimens followed the ionized path provided by LIP. The result was well focused melted spots.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.4
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• pp.322-330
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• 2007

Backgrounds: To overcome limited amount of autogenous mucosa for the reconstruction of various mucosal defect including oral mucosal defect, tissue engineered mucosa has been recently introduced. However, introduced conventional technique of tissue engineered mucosa still have serious pitfalls such as long fabrication time, fragility of the reconstructed mucosa, and complexity of the technique. Aim of the study: To examine whether the complex of preconfluent autologous keratinocytes and autologous PRP(Platelet rich plasma) can reconstruct oral mucosa on the muscular flap with easier and faster way compared to conventional mucosal tissue engineering technique. Materials and methods: One day before the operation, oral mucosa(3mm in diameter) were taken and treated for extraction of oral keratinocytes according to the routine manner. The day of operation, oral keratinocytes were prepared in the laboratory and then moved to the operating theater. Autologous PRP was also prepared and then mixed with oral keratinocytes just before grafting on the prepared muscular flap. After keratinocyte-PRP complex was seated, then a sterilized rubber sheet was placed on the graft and the elevated skin flap was replaced and sutured. Biopsies were proceeded at 3, 5, 7, 14 and 21 days. Tissue samples were evaluated clinically, histologically, and immunohistochemically. Results: All of the oral keratinocyte-PRP complexes were successfully grafted on the recipient sites(100%). On 3 days after the operation, 1-2 continuous epithelial layer and many inflammatory cells were observed. On 5 days after the operation, increase of layers of keratinocyte was observed with less inflammatory response. Thickness of the layers was gradually increased from 7 to 21 days after the operation. Cytokeratin confirms epithelium in every specimen. Conclusions: Preconfluent graft of autogenous oral keratinocytes mixed with autogenous PRP have successfully reconstructed myo-mucosal flap. This technique could be a useful alternative for oral mucosal reconstruction in the near future.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.53.1-53.1
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• 2018

During a major solar eruption, the erupting plasma is possibly out of the equilibrium ionization state because of its rapid heating or cooling. The non-equilibrium ionization process is important in a rapidly evolving system where the thermodynamical time scale is shorter than the ionization or recombination time scales. We investigate the effects of non-equilibrium ionization on EUV and X-ray observations by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory and X-ray Telescope (XRT) on board Hinode. For the investigation, first, we find the emissivities for all the lines of ions of elements using CHIANTI 8.07, and then we find the temperature responses multiplying the emissivities by the effective area for each AIA and XRT passband. Second, we obtain the ion fractions using a time-dependent ionization model (Shen et al. 2015), which uses an eigenvalue method, for all the lines of ion, as a function of temperature, and a characteristic time scale, $n_et$, where $n_e$ and t are density and time, respectively. Lastly, the ion fractions are multiplied to the temperature response for each passband, which results in a 2D grid for each combination of temperature and the characteristic time scale. This is the set of passband responses for plasma that is rapidly ionized in a current sheet or a shock. We investigate an observed event which has a relatively large uncertainty in an analysis using a differential emission measure method assuming equilibrium ionization state. We verify whether the observed coronal plasmas are in non-equilibrium or equilibrium ionization state using the passband responses.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.158-162
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• 2015

To substitute indium tin oxide (ITO), many substituents have been studied such as metal nanowires, carbon based materials, 2D materials, and conducting polymers. These materials are not good enough to apply to an electrode because theses exhibit relatively high resistance. So metal grids are required as an additionalelectrode to improve the conductivities of substituents. The metal grids were printed by electrohydrodynamic printing system using Ag nanoparticle based ink. The Ag grids showed high uniformity and the line width was about $10{\mu}m$. The Ag nanoparticles are surrounded by dispersants such as unimolecular and polymer to prevent aggregation between Ag nanoparticles. The dispersants lead to low conductivity of Ag grids. Thus, the sintering process of Ag nanoparticles is strongly recommended to remove dispersants and connect each nanoparticles. For sintering process, the interface and microstructure of the Ag grid were controlled in 1.0 torr Ar atmosphere at aound $400^{\circ}C$ of temperature. From the sintering process, the uniformity of the Ag grid was improved and the defects on the Ag grids were reduced. As a result, the resistivity of Ag grid was greatly reduced up to $5.03({\pm}0.10){\times}10^{-6}{\Omega}{\cdot}cm$. The metal grids embedded substrates containing low pressure Ar sintered Ag grids showed 90.4% of transmittance in visible range with $0.43{\Omega}/{\square}$ of sheet resistance.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.47-52
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• 2013

Graphene has been synthesized on 100- and 300-nm-thick Ni/$SiO_2$/Si substrates with $CH_4$ gas (1 SCCM) diluted in mixed gases of 10% $H_2$ and 90% Ar (99 SCCM) at $900^{\circ}C$ by using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The film morphology of 100-nm-thick Ni changed to islands on $SiO_2$/Si substrate after heat treatment at $900^{\circ}C$ for 2 min because of grain growth, whereas 300-nm-thick Ni still maintained a film morphology. Interestingly, suspended graphene was formed among Ni islands on 100-nm-thick Ni/$SiO_2$/Si substrate for the very short growth of 1 sec. In addition, the size of the graphene domains was much larger than that of Ni grains of 300-nm-thick Ni/$SiO_2$/Si substrate. These results suggest that graphene growth is strongly governed by the direct formation of graphene on the Ni surface due to reactive carbon radicals highly activated by ICP, rather than to well-known carbon precipitation from carbon-containing Ni. The D peak intensity of the Raman spectrum of graphene on 300-nm-thick Ni/$SiO_2$/Si was negligible, suggesting that high-quality graphene was formed. The 2D to G peak intensity ratio and the full-width at half maximum of the 2D peak were approximately 2.6 and $47cm^{-1}$, respectively. The several-layer graphene showed a low sheet resistance value of $718{\Omega}/sq$ and a high light transmittance of 87% at 550 nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.430-430
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• 2008

Using multi plasma enhanced chemical vapor deposition system (Multi-PECVD), p-a-Si:H deposition layer as a $p^+$ region which was annealed by laser (Q-switched fiber laser, $\lambda$ = 1064 nm) on an n-type single crystalline Si (100) plane circle wafer was prepared as new doping method for single crystalline interdigitated back contact (IBC) solar cells. As lots of earlier studies implemented, most cases dealt with the excimer (excited dimer) laserannealing or crystallization of boron with the ultraviolet wavelength range and $10^{-9}$ sec pulse duration. In this study, the Q-switched fiber laser which has higher power, longer wavelength of infrared range ($\lambda$ = 1064 nm) and longer pulse duration of $10^{-8}$ sec than excimer laser was introduced for uniformly deposited p-a-Si:H layer to be annealed and to make sheet resistance expectable as an important process for IBC solar cell $p^+$ layer on a polished n-type Si circle wafer. A $525{\mu}m$ thick n-type Si semiconductor circle wafer of (100) plane which was dipped in a buffered hydrofluoric acid solution for 30 seconds was mounted on the Multi-PECVD system for p-a-Si:H deposition layer with the ratio of $SiH_4:H_2:B_2H_6$ = 30:120:30, at $200^{\circ}C$, 50 W power, 0.2 Torr pressure for 20 minutes. 15 mm $\times$ 15 mm size laser cut samples were annealed by fiber laser with different sets of power levels and frequencies. By comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 50 mm/s of mark speed, 160 kHz of period, 21 % of power level with continuous wave mode of scanner lens showed the features of small difference of lifetime and lowering sheet resistance than before the fiber laser treatment with not much surface damages. Diode level device was made to confirm these experimental results by measuring C-V, I-V characteristics. Uniform and expectable boron doped layer can play an important role to predict the efficiency during the fabricating process of IBC solar cells.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.42-42
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• 2004

Recently, Pi2 pulsations during the intervals of extremely quiet magnetospheric conditions (Kp = 0$\^$+/) have been reported by Sutcliffe and Lyons (2002). The authors observed several Pi2 bursts occurred simultaneously at high (magnetic latitude = 71$^{\circ}$) and low (42$^{\circ}$) latitudes during the absence of magnetospheric substorms and found that the bursts are strongly correlated with poleward boundary intensifications (PBIs), associated with enhancements of energetic ion fluxes observed by the Geotail satellite at Xgsm - -12 Re to -17 Re and Ygsm - 12 Re to 10 Re in the plasma sheet. (omitted)

• Journal of Korean Vacuum Science & Technology
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• v.3 no.2
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• pp.101-106
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• 1999

The main consideration factor to design a magnetron of the sputtering system for TFT-LCD metallization is high sheet resistance (Rs) uniformity which is provided by the high target erosion and high current efficiency. The present study has developed a rectangular magnetron for TFT-LCD to bve considered full target erosion and high film uniformity. After an aluminum-2 at.% and alloy target was installed in a magnetron source and the film was deposited on the glass of 600${\times}$720 mm, the Rs uniformity of the deposited film was measured as functions of the magnet tilt and magnet scanning configuration. And the target erosion profile was observed with the target voltage. When sputtered at 4mtorr and 10kW, the magnet tilt for the high Rs uniformity of 8.38% was 7mm. The plasma voltage at the dwell home and end for full-face target erosion, when scanned the magnetron was 120% compared to the mean voltage of the other area.