• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.4
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• pp.338-342
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• 2010

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. The MWCNT films were investigated as a transparent electrode for the solar cell, OLED, and field-emission display. MWCNT films were fabricated by air spray method, whose process is quite low-costed, using the multi-walled CNTs solution on glass substrates. Moreover, the most stable film was fabricated when the spraying time was 60 sec. The film that was sprayed with the MWCNT dispersion for 60 sec, has 300nm thick. And its electric resistivity, transmittance rate, mobility and carrier concentration are $6{\times}10^{-2}{\Omega}{\cdot}cm$, 50% at ${\lambda}=550mm$, $4.3{\times}10^{-2}cm^2/V{\cdot}s$ and $2.1{\times}10^{21}cm^{-3}$, respectively. Also, absorption energy of MWCNT films show from 3.9 eV to 4.6 eV. Furthermore, we can use MWCNT films fabricated by the spray method for the transparent electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.63-66
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• 1992

Using an aromatic system, we made a ultra thin insulator through LB-method. We measured and wrote down afternating currant characteristics of ultraviolet rays extincting-spectrum and I.R extincting-spectrum. We surveyed the thickness of a film through X-ray diffracting method and certified about $4{\AA}$ by the layer. Measuring the characteristics of direct current voltage and electric current with this sample, we produced its conductivity and discovered that this sample had a god insulating performance. Addition to this, we measured the characteristics of voltage and electric current, and the temperature dependency of conductivity in a high voltage system and with these results tried to interpret a mechanism of conduction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.266-269
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• 2012

The most recently IGBT (insulated gate bipolar mode transistor) devices are in the most current conduction capable devices and designed to the big switching power device. Use this number of the devices are need to high voltage and low on-state voltage drop. And then in this paper design of field stop IGBT is insert N buffer layer structure in NPT planar IGBT and optimization design of field stop IGBT and trench field stop IGBT, both devices have a comparative analysis and reflection of the electrical characteristics. As a simulation result, trench field stop IGBT is electrical characteristics better than field stop IGBT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.261-265
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• 2012

IGBT(insulated gate bipolar transistor) is outstanding device for current conduction capabilities. IGBT design to control the large power switching device for power supply, converter, solar converter, electric home appliances, etc. like this IGBT device can be used in many places so to increase the efficiency of the various structures are coming. in this paper optimization design of planar type IGBT and planar field stop IGBT, and both devices have a comparative analysis and reflection of the electrical characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.316-318
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• 2003

양자우물 구조를 사용한 HEMT(High Electron Mobility Transistor)는 고속 스위칭 소자와 초고주파 통신용 소자 및 센서에에 우수한 동작특성을 갖고 있다. 본 논문에서는 AlInAs/InP HEMT의 heterostructure를 파동방정식과 Poisson 방정식을 self-consistent 한 방법으로 해석하였다. 파동방정식으로 junction의 전자농도를 계산하고, Poisson 방정식을 해석하여 potential profile에 의한 전자 농도가 heterostructure에서 self-consistent가 되도록 연산하였다. 끝으로 AlInAs/InP 구조에서 positively ionized donor, valance band에서의 hole, conduction band의 free electron과 구조내의 2DEG를 AlGaAs/GaAs 및 AlGaAs/InGaAs/GaAs와 비교하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.90-93
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• 1996

The conduction mechanisms of the off-current in low temperature ($\leq$600$^{\circ}C$) processed polycrystalline silicon thin film transistors (LTP poly-Si TFT's) has been systematically studied. Especially, the temperature and bias dependence of the off-current between unpassivated and passivated poly-Si TFT's was investigated and compared. The off-current of unpassivated poly-Si TFT's is due to a resistive current at low gate and drain voltage, thermal emission current at high gate, low drain voltage, and field enhanced thermal emission current in the depletion region near the drain at high gate and drain voltage. After hydrogenation, it was observed that the off-currents were remarkably reduced by plasma-hydrogenation. It was also observed that the off-currents of the passivated poly-Si TFT's are more critically dependent on temperature rather than electric field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.252-255
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• 1996

Superconducting current lead is one of the promising applications of the oxide high-Tc superconductors, because they have the advantage of decreasing heat conduction to low temperature region, comparing with a conventional cooper alloy lead. High critical current density is a key factor for the applications such as current lead. (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$\_$x/ high Tc superconductor haute been investigated in terms of critical current density. Bi-2223 superconducting current lead made by CIP and solid state sintering process. Bi-2223 current lead that heat treated at 836$^{\circ}C$ for 240 h in 1/13 P$\_$O$_2$/ had over 150 A/$\textrm{cm}^2$ of critical current density at 77K. We knew that the superconducting properties of tube type current leads were better than rods type of them. And we investigated the relation of Bi-2223 formation and heat treatment condition by XRD and SEM analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.149-150
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• 2005

According to the trend for electric power equipment of high capacity and reduction of its size, the needs for the new high performance electric equipments become more and more important. On of the possible solution is high temperature superconducting (HTS) power application. Following the successful development of practical HTS wires, there have been renewed activities in developing superconducting power equipment. HTS equipments have to be operated in a coolant such as liquid nitrogen ($LN_2$) or cooled by conduction-cooling method such as using Gifford-McMahon (G-M) cryocooler to maintain the temperature below critical level. In this paper, the dielectric strength of unfilled epoxy and filled epoxy in $LN_2$ was analyzed. The filled epoxy composite not only compensates for this fragile property but enhances its dielectric strength.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.376-382
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• 2001

Magnetic and transport properties in the ceramic specimen of L $a_{0.7}$S $r_{0.3}$Fe $O_3$ with orthohombic structure has been investigated. Weak ferromagnetism has been observed in a ceramic sample of L $a_{0.7}$S $r_{0.3}$Fe $O_3$. Large dielectric relaxation of Debye type is observed in paramagnetic states within the temperature range of 130K~200K. From the temperature dependence of the characteristic frequency, we concluded that the elementary process of the dispersion is related to holes hopping between F $e^{3+}$ and F $e^{4+}$ ions. The temperature dependencies of thermoelectric power and Dc conductivity suggest that the charge carrier responsible for the conduction are strongly localized. These experimental results have been interpreted in terms of a hopping process involving small polaron.n.laron.n.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.397-400
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• 1996

We investigated electric and dielectric properties of MIM device using Maleate Copolymer LB films. The thickness of maleate copolymer LB film by ellipsometry measurements and X-ray diffraction pattern was about 27~30[ ]. The maleate copolymer 13 film have the property of insulator like organic ultra-thin film. The electric conduction was Schottky current measured by I-V characteristics, and the conductivity was 10$^{-15}$ ~10$^{-14}$ [S/cm]. Dielectric constant was about 5.0~6.0 by various measurement: I-V, frequency-depenent dielectric properties. Schottky barrier was about 0.9 ~1.0(eV). By relation between log I and 1/T, activation energy baa 0.74(eV). Frequency-depenent dielectric properties wart orientational polarization by the dipole.