• ETRI Journal
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• 제11권4호
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• pp.75-83
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• 1989

The diffusion mechanism of Si in GaAs was investigated using different diffusion sources based on the Si-Ga-As ternary phase equilibria. The Si profiles are measured with secondary ion mass spectrometry and differ significantly for sources taken from the different phase fields in the ternary phase diagram. Neutral As vacancy diffusion is proposed for acceptor Si diffusion anneals using a Ga - Si - GaAs source. Donor Si diffusion using As - rich sources and a Si -GaAs tie line source shows concentration dependent diffusion behavior. Concentration dependent diffusion coefficients of donor Si for As - rich source diffusion were found to be related to net ionized donor concentration and showed three regimes of different behavior: saturation regime, intermediate regime,and intrinsic regime. Ga vacancies are proposed to be responsible for donor Si diffusionin GaAs: $Si_Ga^+V_Ga^-$ (donor Si -acceptor Gavacancy) complex for the extrinsic regime and neutral $V_G$a, for the intrinsic regime.The Si - GaAs tie line source resulted in two branch profiles, intermediate between the As - rich and the Ga - rich source diffusion cases.

• Journal of Pharmaceutical Investigation
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• 제26권2호
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• pp.99-103
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• 1996

Effects of glycerin and PEG 400 in donor and receptor solutions upon skin permeation of drug were investigated. Deoxycortisone was used as a model compound. In vitro skin permeation study with freshly excised hairless mouse skin was performed and the steady-state skin permeation rates of the drug were determined in different fractions of glycerin or PEG 400 in donor and receptor solutions. Glycerin in donor solution didn't show any effect on the skin permeation rate of deoxycortisone. However glycerin in receptor solution showed significant effect on the skin permeation rate of the drug. In glycerin, there's a critical concentration for balancing hydration and dehydration of skin. At low concentration, less than 20 %, glycerin showed the enhancement of the flux due to the hydration effect of skin. At high concentration, more than 30 %, glycerin retard the permeation rate which might be due to the dehydration effect on the dermis layer. Since dermis has more water content than the stratum corneum, the steady state skin permeation rates were more influenced when glycerin was in receptor solution than that of in donor solution. PEG 400 aqueous solutions doesn't affect the steady state permeation rate of deoxycortisone significantly.

• 한국광학회지
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• 제2권4호
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• pp.203-208
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• 1991

모드동기된 아르곤 이온 레이저를 여기광원으로 사용한 시간상관 단일광자 계수장치를 이용하여 에틸렌글리콜 용매 내에서 Rhodamine 6G에서 Malachite Green으로의 비복사 에너지전달과정을 연구하였다. 측정된 donor의 형광소멸곡선을 full-fitting 방법으로 분석 처리하여 acceptor 농도의 변화에 따른 환산농도와 임계전이거리를 구했다. donor의 농도가 acceptor의 농도 보다 클때는 donor-donor의 원거리 쌍극자 모멘트에 의한 에너지 이주 효과를 고려해야하며 Forster 모델 보다 Huber 모델이 더 적절하였다.

• 한국수소및신에너지학회논문집
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• 제1권1호
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• pp.48-54
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• 1989

Semiconductive property of the passivating $TiO_2$ film was investigated by measuring the impedance of passivated titanium electrode in a 0.1 N NaOH solution. The passive film was prepared galvanostatically with $10mA/cm^2$ at formation potential of 50 V in a 1 N $H_2SO_4$ solution. The impedance measurement was conducted by superimposing an ac voltage of 5 m V amplitude with the frequency ranging from 5 to 10000 Hz on a dc bias (applied potential). The donor distribution in the film was depicted from the analysis of the non-linear slope of Mott-Schottky plot. The region with nearly constant concentration of donors near the electrolyte/film interface amounts at about 60 percent of the total film thickness and donor concentration increases largely with distance from the surface in an inner region near the film/metal interface. In a region of the film/metal interface the donor concentration showed a frequency dependence greater than in a region of the electrolyte/film interface. The result of donor concentration against frequency suggests a transition from crystalline to amorphous state with distance from the electrolyte/film interface in the passivating $TiO_2$ films. This is also confirmed by the ac conductivity measurement.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.40-47
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• 1995

Electrical properties of ZnO ceramics based on Bi oxide was investigated in relation to sintering temperature. In the temperature range >$1150^{\circ}C$ to >$1350^{\circ}C$ the grain size increased from 9.mu.m to 20.mu.m when the sintering temperature was raised. The leakage current in the low voltage range increased as the potential barrier decreases, which is caused by increasing the grain size at high temperature. The dielectric characteristics of the ZnO ceramics was also affected by sintering temperature. Large dielectric constant was attributed, to the grainboundary layer of polycrystalline ZnO ceramics and decreasing grainboundary width. The variation of breakdown voltage with sintering temperature was attributed to the change of the donor concentration in the ZnO grain and grain size. The results showed that breakdown voltage increased decreasing grain size and donor concentration. Nonohmic coefficient was associated with the lower breakdown voltage per grainboundary layer due to the grain growth and higher donor concentration.

• Transactions on Electrical and Electronic Materials
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• 제2권4호
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• pp.24-29
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• 2001

GaN films were grown for various Mg doping concentrations in metal-organic chemical vapor deposition. Below the Mg concentration of 10$^{19}$ ㎤, the thermally annealed sample shows the compensated phase to n-type GaN in Hall measurement. In the MB concentration of 4$\times$10$^{19}$ ㎤ corresponding to the hole carrier concentration of 2.6$\times$1$^{19}$ ㎤ there exists a photoluminescence center of the donor and the acceptor pair transition of the 3.28-eV band. This center is correlated with the defects for a shallow donor of the $V_{Ga}$ and for an acceptor of $Mg_{Ga}$ . The acceptor level shows the binding energy of 0.2-0.25 eV, which was observed by the photon energy of the photocurrent signal of 3.02-3.31 eV. Above the Mg concentration of 4$\times$10$^{19}$ ㎤, both the Mg doping level and Mg concentration were saturated and there Is a photoluminescence center of a deep donor and an acceptor pair transition of the 2.76-eV blue band.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.465-468
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• 1987

This paper describes a model to calculate the equilibrium electron density of MODFET at the interface that takes into account the simultaneous shallow and deep level in the Al-GaAs layer. In the present study we have made an investigation of the interface electron density with different values of the AlGaAs doping density and spacer layer thickness, considering simultaneously two doner levels. In this case, the ratio of the shallow to the deep donor concentraction is considered. From the comparison with early experimental results we could find the deep level and that the deep donor concentration is about 50% with the Al mole fraction X ${\sim}0.3$, activation energy Edx=65meV, temperature $77^{\circ}K$ and spacer thickness range $50A{\sim}100A$. Also we have investigated the effect of the temperature. As temperature increase, at critical mole fraction X the nature of the donor concentration changes from $\Gamma$ to L and X.

• 자연과학논문집
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• 제13권1호
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• pp.51-63
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• 2003

$1-10^{-20}$atm의 산소 압력과 700K 및 1200K의 등온상태에서 Donor를 첨가한 $BaTiO_3$의 전기전도도를 조사하여 결함의 형태를 조사하였다. Donor를 첨가한 $BaTiO_3$에서 Donor의 첨가량이 증가함에 따라 최소 전기도도를 나타내는 극소점의 위치가 순수한 경우에 비아여 어느 정도 이동이 있었다. 이러한 극소점 위치의 이동으로 불순물의 상대적 함유량을 비교할 수 있었다. 매우 낮은 산소압력에서는 Dopant의 양에 무관하게 전도도 값이 일정하였으며 이러한 현상은 환원반응이 주된 원인임을 알았다.

• 전기학회논문지
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• 제65권10호
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• pp.1697-1701
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• 2016

The leakage conduction and critical voltage characteristic of ZnO ceramic were investigated as a function of $Sb_2O_3$ concentration. Leakage conduction in the ohmic region increased with increasing $Sb_2O_3$ concentration and was attributed to the potential barrier height. The nonlinear coefficient increased with an increasing amount of $Sb_2O_3$. It was found that increases in the apparent critical voltages were associated with the lowered donor concentration in the grain boundary of between two ZnO grains. And the decrease of donor concentration on doping with $Sb_2O_3$ additive was attributed to the lowered capacitance in the grain boundary layer.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.391-394
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• 2003

The applicability of in situ microbial filter or biobarrier technology for the remediation of soil and groundwater contaminated with chlorinated solvents was investigated. The efficiency and rates of reductive dechlorination of chlorinated solvents are known to be highly dependent on hydrogen concentration. In this study, the effect of electron donors on the reductive dechlorination of PCE was investigated using vermicompost (worm casting) and peat as permeable reactive barrier medium The effect of organic acids (lactate, butyrate and benzoate), yeast extract and vitamin $B_{l2}$ on the reductive dechlorination was investigated. Compared to the control (no electron donor added), addition of electron donors stimulated the dechlorinated rate. Among the electron donor treatments, lactate/benzoate amendment exhibited the highest dechlorination rate. Since vermicompost and peat are inexpensive and biodegradable and have high sorption capacity, they could be successfully used as biobarrier media, especially when electron donors (for example, lactate/benzoate) are added.d.