• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.77-78
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• 2009

We report numerical simulations to investigate of the dependence of the on/off current ratio and channel charge distributions in silicon nanowire (SiNW) field-effect transistors (FETs) on the channel width and thicknesses. In order to investigate the transport behavior in devices with different channel geometries, we have performed detailed two-dimensional simulations of SiNWFETs and control FETs with a fixed channel length L of 10um, but varying the channel width W from 5nm to 5um, and thickness t from 10nm to 30nm. We have shown that $Q_{ON}/Q_{OFF}$ drastically decreases (from ${\sim}2.9{\times}10^4$ to ${\sim}9.8{\times}10^3$) as the channel thickness increases (from 10nm to 30nm). As a result of the simulation using a quantum model, even higher charge density in the bottom of SiNW channel was observed than that in the bottom of control channel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.253-260
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• 2012

IGBT (insulated gate bipolar transistor) have received wide attention because of their high current conduction and good switching characteristics. To reduce the power loss of IGBT, the on state voltage drop should be lowered and the switching time should be shorted. However, there is Trade-off between the breakdown voltage and the on state voltage drop. To achieving good electrical characteristics, field stop IGBT (FS IGBT) is proposed. In this paper, 1,200 V planar gate non punch-through IGBT (planar gate NPT IGBT), planar gate FS IGBT and trench gate FS IGBT is designed and optimized. The simulation results are compared with each three structures. In results, we optain optimal design parameters and confirm excellence of trench gate FS IGBT. Experimental result by using medici, shows 40% improvement of on state voltage drop.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.180.2-180.2
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• 2014

Opening a bandgap by forming graphene nanoribbons (GNRs) and tailoring their properties via doping is a promising direction to achieve graphene-based advanced electronic devices. Applying a first-principles computational approach combining density functional theory (DFT) and DFT-based non-equilibrium Green's function (NEGF) calculation, we herein study the structural, electronic, and charge transport properties of boron-nitrogen binary edge doped GNRs and show that it can achieve novel doping effects that are absent for the single B or N doping. For the armchair GNRs, we find that the B-N edge co-doping almost perfectly recovers the conductance of pristine GNRs. For the zigzag GNRs, it is found to support spatially and energetically spin-polarized currents in the absence of magnetic electrodes or external gate fields: The spin-up (spin-down) currents along the B-N undoped edge and in the valence (conduction) band edge region. This may lead to a novel scheme of graphene band engineering and benefit the design of graphene-based spintronic devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.347-351
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• 2003

A p-$CdIn_2Te_4$ single crystal has been grown by the Bridgman method without a seed crystal in a tree-stage vertical electric furnace. From photocurrent measurements, it was found that three peaks, A, B, and C, corresponded to an intrinsic transition due to the band-to-band transition from the valence band states ${\Gamma}_7(A),\;{\Gamma}_6(B),\;and\;{\Gamma}_7(C)$ to the conduction band state ${\Gamma}_6$, respectively. Also, the valence band splitting of the $CdIn_2Te_4$ crystal has been confirmed by photocurrent spectroscopy. The crystal field splitting and the spin orbit splitting were obtained to be 0.2360 and 0.1119 eV, respectively. Also, the temperature dependence of the band gap energy of the $CdIn_2Te_4$ crystal has been driven as the following equation of $E_g(T)\;=E_g(0)\;-\;(9.43\;{\times}\;10^{-3})T^2/(2676\;+\;T)$. In this equation, the Eg(0) was estimated to be 1.4750, 1.7110, and 1.8229 eV at the valence band state A, B, and C, respectively. The band gap energy of the p-$CdIn_2Te_4$ at room temperature was determined to be 1.2023 eV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.111-114
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• 2003

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature ($T_{c,zero}$ : 90 K) and critical current density ($2354\;A/cm^2$). Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.510-513
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• 2003

In this paper, we have investigated the physical, dielectric and electrical conduction properties of polyethylene terephthalate(PET) film due to temperature variation. From FT-IR spectrum as an analysis of physical properties, the strong absorption in wavenumber 1019[$cm^{-1}$], 1266[$cm^{-1}$], and 1752[$cm^{-1}$] observed by the C=O and benzene ring. the characteristics of volume resistivity used to highmegohm meter is measured from 1 to 10 minutes when the specimen applied the voltage according to the step voltage appling method. and dielectric characteristics were measured in the temperature range from room temperature to 120[$^{\circ}C$] due to frequency variation.. also we measured in the voltage rang of 1[V] to 20[V] according to the voltage application method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.459-462
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• 2001

Interface effects on properties of NTC thermistors having Mn-Co-O spinel crytal structure system are analyzed by a mixing rule in case of mixed types and layered types between CuO and $Al_{2}O_{3}$ added compounds. With adding CuO and $Al_{2}O_{3}$, The compounds form completely solid solution and their resistance and B constant are changed due to the variation of conduction electrons by their ionic substitutions. The properties of mixed NTC thermistors are depended on the logarithmic mixing rule by a dispersed phase and they show slightly lower values due to the lattice mixing affect in compared with calculated values. The resistance of layered NTC thennistors is depended upon the series mixing rule containing the value of an interface layer and effected by the variation of its thickness, and it is changed rapidly to the logarithmic mixing rule by the connection between two layers with increasing the interface layer.

• Journal of Power Electronics
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• v.13 no.4
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• pp.636-646
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• 2013

A single-phase tapped-inductor boost converter has been proposed previously. However, detailed characterization and performance analysis were not conducted. This paper presents a detailed characterization, performance analysis, and design expressions of a single-phase tapped-coupled-inductor boost converter. Expressions are derived for average and RMS input current as well as for RMS input and output capacitor current ripple. A systematic approach for sizing the tapped-coupled inductor, active switch, and output diode is presented; such approach has not been reported in related literature. This study reveals that sizing of the inductor has to be based on current ripple requirement, turns ratio, and load. Conditions that produce discontinuous inductor current are also discussed. Analysis of a non-ideal converter operating in continuous conduction mode is also conducted. The expression for the voltage ratio considering the coupling coefficient is derived. The suitability of the converter for high-voltage step-up applications is evaluated. Factors that affect the voltage boost ratio are also identified. The effects of duty ratio and load variation on the performance of the converter are also investigated. The theoretically derived characteristics are validated through simulations. Experimental results obtained at a low power level are included to validate the analytical and simulation results. A good agreement is observed among the analytical, simulation, and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.293-294
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• 2005

We have investigated dielectric properties depending on frequency in organic light -emitting diodes using 8-hydroxyquinoline aluminum ($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using impedance of characteristics. impedance characteristics was measured complex impedance Z and phase $\Theta$ in the frequency range of 40 Hz to $10^8$ Hz. We obtained complex electrical conductivity, dielectric constant, and loss tangent (tan$\delta$) of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

• Electrical & Electronic Materials
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• v.5 no.4
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• pp.421-429
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• 1992

본 연구에서는 (Sr.Pb)TiO$_{3}$계 세라믹을 고압용 세라믹 캐패시터로 응용하기 위하여 일반적인 세라믹 소성법으로 제작하였으며 Bi$_{2}$O$_{3}$. 3TiO$_{2}$의 첨가량에 따른 전기전도 및 DC 절연파괴 특성을 조사하였다. 전도전류는 측정온도의 상승과 Bi$_{2}$O$_{3}$.3TiO$_{2}$의 첨가량이 증가함에 따라 상승하였다. 실온에서 전도전류는 전계에 따라 3영역으로 나누어졌다. 전계 15[kV/cm]이하의 영역에서는 오음의 법칙이 성립하는 이온전도가 나타났으며 전계 15[kV/cm]~40[kV/cm]인 영역에서는 전계에 강요된 강유전성 분극의 반전게에 기인하여 전류의 포화현상이 나타났다. 전계 40[kV/cm] 이상의 영역에서는 공간전하제한전류에 관련된 차일드법칙이 성립하였다. DC 절연파괴 강도는 측정온도의 상승과 Bi$_{2}$O$_{3}$.3TiO$_{2}$의 첨가량이 증가함에 따라 감소하였다. 온도 100[.deg.C] 이하에서는 전자적파괴가 일어났으며 100[.deg.C] 이상에서는 주울열과 유전손실에 의한 열적파괴가 나타났다.