Al0.2Ga0.8As/SI-GaAs 구조의 Photoreflectance 특성

한병국,김동렬 慶山大學校 基礎科學硏究所 1999 基礎科學 Vol.3 No.-

Al??Ga??As/GaAs 구조에 대해 photoreflectance(PR) 측정를 수행하였으며, PR 스펙트럼이 GaAs 기판으로부터 근원이되는 두 개의 신호의 중첩으로 되어 있음을 관측하였다. modulation beam power dependence으로부터, GaAs에서 PR신호를 야기시키는 photo-carrier가 계면 부근에서 발생됨이 밝혀졌다. GaAs 기판으로부터의 PR신호가 높은 변조 주파수에서 다른 기여(contribution)와 분리되어 질 수 있음을 증명했으며, 변조 주파수 의존성 측정을 통하여 이러한 것이 photo-carrier의 lifetime의 차로인한 결과로 나타남을 밝혔다. We have performed photoreflectance(PR) measurement for Al0.2Ga0.8As/GaAs structure and have observed that PR spectrum is superposition of two signals which originate from GaAs substrate. From the modulation beam power dependence, we reveal that the photo-carriers, which cause the PR signals from the GaAs, are generated at the vicinity of the interface. We have also demonstrated that PR signals from GaAs substrate can be separated from the other contributions at a high modulation frequency. Through measuring the modulation frequency dependence, we have confirmed that this results from the difference of the lifetimes of photo-carriers.

CPLD를 利用한 電力變換用 專用칩 開發에 關한 硏究

韓運東,林炳國 충주대 2001 한국교통대학교 논문집 Vol.35 No.2

The use of HDL(Hardware Description Language) is now central to the ASIC(Application Specific Integrated Circuit).HDL-based ASIC can simplify the process of development and has a competition in market because it reduce the consuming time for the design of IC(Integrated circuit) in system level.Therefore, the development of power electronics system on chip (SOC), to design microcontroller and switching logic as one chip, is required extremely for the purpose of having reliability and low cost in power electronics which is based on switching elements.The major application of SOC is variable converter, active filter, inverter for induction motor, UPS and power supply with a view to reducing electromagnetic pollution.

CBE(chemical beam epitaxy)로 성장한 l.lum 파장대를 가지는 InGaAsP의 PR(photoreflectance) 특성연구

한병국,김동열 慶山大學校 1996 論文集 Vol.14 No.1

InGaAsP with 1.1㎛ wavelength was grown by chemical beam epitaxy (CBE). Pure arsine (AsH₃) and phosphine(PH₃) gases were used as group V sources. For the group Ⅲ Sources, TEGa, TMIn were used. InGaAsP epilayer was grown on SI-InP substrate and has a l-㎛ thick. We investigated characteristics of InGaAsP using photoreflectance(PR) and photoluminescence(PL) spectroscopy. From PR measurement, the signal of InGaAsP shows well-defined Franz-Keldysh oscillation (FKO) whose peaks provide energy gap. The energy gap of InGaAsP has been a good agreement with the peak energy of PL.

Avalanche 주입에 의한 SiO_(2)층 내에 전하 trapping 현상

한병국 慶山大學校 1993 論文集 Vol.11 No.1

We have studied by capacitance and I-V measurements the detail of avalanche injection of electrons into sillicon dioxide. In the process of avalanche injection of electrons into silicon dioxide, besides electron trapping in the bulk of the oxide, there are slow and fast interface states generated. The slow states are donors and positively charged when empty. Together with positive charge in the interface states, they compensate the negative bulk charge to give the turn -around effect. As a function of avalanche fluence F A, the flatband voltage shift did not increase monotonically. Instead, after a maximum voltage shift was reached, the flatband voltage decreased with further injection of electrons. The turn-around effect is observed after 0.1 to 0.15C-cm-2 are injected into an oxide. The effect was explained by the generation of interface states. When heated under (+)5V bias to 100℃, slow states are filled by electrons, whereas for negative bias the states are empty, giving a high positive charge density

Avalanche Electron Trapping에 의한 건식산화막의 두께의존성에 관한 연구

한병국 慶山大學校 1998 論文集 Vol.16 No.1

In MOS (metal-oxide-semiconductor) capacitors with the dry oxide grown thermally, the avalanche electron trapping behavior has been measured as a faction of thickness at 110℃. Flat-band voltage shifts △V_(FB) is dependent on oxide thickness d_(ox)^(2) for dry oxide samples subjected to PMA(postmetalization annealing). This result, and supporting evidence from photo I-V measurments, indicatedthat electron trapping centers were distributed uniformly throughout the oxide layer. For the dry oxides, which were not given PMA, △V_(FB) scaled approximately as d_(ox), and the trapped charge centroid, determined from photo I-V measurements on several 900Å thick samples, was ∼0.32d_(ox).

Ce_(0.8)Zr_(0.2)O₂ 촉매를 이용한 Dimethyl Carbonate 합성에서 탈수제 첨가의 영향

한기보,전진혁,박노국,이종대,류시옥,이태진,이병권,안병성 한국공업화학회 2004 응용화학 Vol.8 No.1

The effect of dehydrating agent in DMC(dimethyl carbonate) synthesis from methanol and carbon dioxide over Ce_(0.8)Zr_(0.2)O₂ catalyst was studied in this work. Ce_(0.8)Zr_(0.2)O₂ catalyst having the best activity among Ce_(1-x)Zr_(x)O₂ catalysts was selected. We could supposed that the addition of dehydrating agents improved the DMC yield by H₂O elimination. When the dehydrating agents such as Na_(2)SO₄ or K₂SO₄ was added into the synthesis of DMC, the formation amount of DMC increased to about 0.8∼0.9 mmol through the elimination of formed H₂O as by-product.

GaAs/AlAs 초격자의 photoluminescence 특성 연구

한병국 慶山大學校 基礎科學硏究所 2000 基礎科學 Vol.4 No.2

MBE(molecular beam epitaxy)를 이용하여 15 monolayer의 두께를 가지는 GaAs/AlAs 초격자를 제작하였다. 특성 연구를 위해 레이저 세기와 온도에 따른 photoluminescence(PL)를 측정하였다. 여기레이저 세기에 따른 PL 강도를 logalithmic plot한 결과 거의 직선으로 나타났으며, 이로부터 상온에서의 재결합과정이 excitomic-like transition에 의한 것으로 분석되었다. 격자온도가 감소할 때, GaAs/AlAs 초격자에서의 Cl-Hl subband 에너지 값은 GaAs 온도 의존성에 따라 증가하였고, 7.2K에서 약 4meV의 차이를 보였다. 이 값은 다른 양질의 양자우물 시료에서 측정된 값과 비슷하게 나타났다. GaAs/AlAs superlattice was grown by molecular beam epitaxy with a thickness of 15 monolayers. We have performed photoluminescence measurement. Measurement were performed as a function of excitation laser power and temperature. The photoluminescence peak intensity as a function of excitation laser power is well described by a straight line on logarithmic plot, indicating that radiative recombination mechanism is excitonic-like transition. Finally, we have showed the temperature dependence of the peak energy of the Hl-Cl transition. When lattice temperature was decreased, the peak energy first increased, following the temperature dependence of the bulk GaAs band gap, and deviated to the lower energy side by about 4meV at 7.2K from extrapolated curve. The observed Stokes shift is in good agreement with previous results on multiple-quantum well sample of the high quality.

대학 캠퍼스 건물 정보 시스템 구축에 관한 연구 : 경희대학교 수원 캠퍼스를 대상으로

소명익,온영태,김선국,김인한,전동훈 경희대학교 산학협력기술연구원 건축도시연구부 1997 건축도시연구소논문집 Vol.17 No.-

The objectiveness of this study is to develop a prototypical university database system by attributing the existing geometrical framework with those physical quantities that are relevant to the formal and functional evaluation of the environment. This system allows interactive access to a global dynamic view of the campus with the ability of interrogation, evaluation, and communication of the campus data management which relate to the fabric of the campus, its utility infrastructure or its inhabitants.

力率 改善用 單相 能動 電子 調節 裝置

林炳國,韓運東 충주대 2001 한국교통대학교 논문집 Vol.36 No.2

A new control method for single-phase shunt active power line conditioners (APLC's) operated under zero average power consumption is proposed in this paper.The amplitude of the sinusoidal source current which is in-phase with the source voltage can be determined from the average value of the instantaneous load power.Then the command current for the shunt APLC is obtained by subtraction the source current from the load current.Neither bulky filter nor time-consuming computation is required.The shunt power compensator supplies all the harmonics of the load current and the source only supplies the fundamental component.Experimental results on a prototype verify the feasibility of the presented scheme.

Ionizing 방사선이 MOS 소자에 미치는 영향에 관한 연구

김말문,한병국,배인호,김인수,유승권 嶺南大學校 基礎科學硏究所 1990 基礎科學硏究 Vol.10 No.-

The analysis of a simple model for radiation-induced space charge buildup in the SiO₂layers of MOS(Metal-Oxide-Semiconductor) is carried out. The model assumes that hole­electron pairs are created in SiO₂layer by the radition and that some of the electrons thus created drift out of SiO₂layer under action of an applied potential across the oxide, V??while corresponding holes become trapped. in these experiments, MOS capacitors having 1100Å and 1950Å SiO₂thickness are exposed to X-ray. Both p-and n-type substrate and Al metal electrodes are used to evaluate characteristics of radiation induced positive charges. From the results of these experiments △V ?? and the number of holes trapped in SiO₂layer strongly depend on oxide thickness, electric field across the oxide layer and absorbed dose. Alwayys C-V(Capacitance-Volage) curve shifts negatively without any relation to substrate types and applied voltage during radiation. This means that trapped charges in the oxide are always positive.