• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.334-338
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• 2003

$BCl_3$고밀도 평판형 유도결합 플라즈마(High Density Planar Inductively Coupled Plasma)를 이용하여 AlGaAs와 InGaP의 건식식각에 대하여 연구하였다. 본 실험에서는 ICP 소스파워(0∼500 W), RIE 척 파워(0-150 W), 공정압력(5∼15 mTorr)의 변화에 따른 AlGaAs와 InGaP의 식각률, 식각단면 그리고 표면 거칠기 등을 분석 하였다. 또, 공정 중 OES(Optical Emission Spectroscopy)를 이용하여 in-situ로 플라즈마를 관찰하였다. $BCl_3$ 유도결합 플라즈마를 이용한 AlGaAs의 식각결과는 우수한 수직측벽도와(>87$^{\circ}$) 깨끗하고 평탄한 표면(RMS roughness = 0.57 nm)을 얻을 수 있었다. 반면, InGaP의 경우에는 식각 후 표면이 다소 거칠어진 것을 확인할 수 있었다. 모든 공정조건에서 AlGaAs의 식각률이 InGaP보다 더 높았다. 이는 $BCl_3$ 유도결합 플라즈마를 이용하여 InGaP을 식각하는 동안 $InCl_{x}$ 라는 휘발성이 낮은 식각부산물이 형성되어 나타난 결과이다. ICP 소스파워와 RIE 척파워가 증가하면 AlGaAs와 InGaP모두 식각률이 증가하였지만, 공정압력의 증가는 식각률의 감소를 가져왔다. 그리고 OES peak세기는 공정압력과 ICP 소스파워의 변화에 따라서는 크게 변화하였지만 RIE 척파워에 따라서는 거의 영향을 받지 않았다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.6-10
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• 2009

In this paper, a selective area growth (SAG) of a GaN/AlGaN double heterostructure (DH) has been performed on r-plane sapphire substrate by using the mixed-source hydride vapor phase epitaxy (HVPE) with multi-sliding boat system. The SAG-GaN/AlGaN DH consists of GaN buffer layer, Te-doped AlGaN n-cladding layer, GaN active layer, Mg-doped AlGaN p-cladding layer, and Mg-doped GaN p-capping layer. The electroluminescence (EL) characteristics show an emission peak of wavelength, 439 nm with a full width at half maximum (FWHM) of approximately 0.64 eV at 20 mA. The I-V measurements show that the turn-on voltage of the SAG-GaN/AlGaN DH is 3.4 V at room temperature. We found that the mixed-source HVPE method with a multi-sliding boat system was one of promising growth methods for III-Nitride LEDs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2420-2424
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• 2009

We have successfully demonstrated of metal-insulator-semiconductor (MIS) capacitors with $Al_2O_3/p-Si$ structures. The $Al_2O_3$ film was grown at $200^{\circ}C$ on H-terminated Si wafer by atomic layer deposition (ALD) system. Trimethylaluminum [$Al(CH_3)_3$, TMA] and $H_2O$ were used as the aluminum and oxygen sources. A cycle of the deposition process consisted of 0.1 s of TMA pulse, 10 s of $N_2$ purge, 0.1 s of $H_2O$ pulse, and 60 s of $N_2$ purge. The 5 nm thick $Al_2O_3$ layer prepared on Si substrate by ALD exhibited excellent electrical properties, including low leakage currents, no mobile charges, and a good interface with Si.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.167-175
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• 1971

A pot experiment with an acid sulfate soil from Kimhae was carried out to find out the cause of toxicity in rice plant. The effect of liming on changes in pH, Eh, Al, and $Fe^{2+}$ in soil and leachate was examined at two-week interval during the growth of rice. Also, total $P_2O_5$, $SiO_2$, Fe and Al contents in plants at harvesting stage were determined. In the early stage, the rice plant in the check soil showed the same healthy growth as did in limed soil even at high Al in soil and leachate. Around panicle forming stage, reddish brown mottlings suddenly infested all over the plants when accompanied with strong reduction, and afterward growth was severely retarded, and finally caused the significant difference in yield. During the strong reduction, significant amount of sulfide was formed only in check soils, but no free $H_2S$ was detected. Appreciable Al was still present in soil and leachate, and $Fe^{2+}$ in check soil was lower than that in limed soil, but $Fe^{2+}$ in leachate was slightly higher. Limed soils were more reduced and produced more $Fe^{2+}$ due to increased microorganism activity in the neutral pH. In the leachate, the check showed slightly higher $Fe^{2+}$ concentration but considerably higher than limed one at later stage. Appreciable amount of Al was detected only in check soil and leachate from transplanting to panicle formation stage. Plant tissues at harvesting stage contained very low P regardless of liming. Uptake of Si was markedly increased by liming. Contents of Fe an Al was markedly higher in check than limed one, but difference in Fe content was more drastic possibly due to more Fe uptake in presence of markedly higher $Fe^{2+}$ in soil and leachate at later growing stage. In conclusion toxic symptom in this acid sulfate soil seems to be primarily due to Al when accompanied with low pH and strong reduction. But association with $Fe^{2+}$ toxicity is not completely excluded. In order to differentiate the effect of $Fe^{2+}$ from that of Al more detailed plant analysis at different stage is required.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.258-264
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• 2004

In this paper, MMIC double balanced star mixer for 40 ㎓ was implemented on GaAs substrate with backside vias. In the design of the MMIC mixer, the design of balun and diode was required. A novel balun structure using microstrip to CPS was presented. The 40 ㎓ balun was designed based on the design experience of the scale-down balun by 2 ㎓. The balun may be suitable for fabrication in MMIC process with backside via and can easily be applied for DBM(Double Balanced Mixer). A Schottky diode was designed and implemented using p-HEMT process considering the compatability with other high frequency MMIC's fabricated on p-HEMT base process. Finally, the double balanced star mixer was fabricated using the balun and the p=HEMP Schottky diode. The measured performance of mixer shows 30 ㏈ conversion loss at 18 ㏈m LO power. This insufficient performance is caused by the unwanted diode at AlGaAs junction in vertical structure of p-HEMT. If the p-HEMT's gate is recessed to AlGaAs layer, and so the diode is eliminated, the mixer's performances will be improved.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.461-464
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• 1987

With the fabrication of Al-$Al_2O_3$-n(p) type Si devices, the analysis and measurement of various characteristics, this study presented the electric physical property theory for the charge distribution of MAS device $Al_2O_3$ films, and inquired out the devices available. In order to study them, Al-(450A)$Al_2O_3$-n(p) type Si was the main objects in the study. They were examined through carrier injection, C-V curves of devices on time, ${\Delta}V_{FB}$-t curves, I-V curves and $Al_2O_3$ film's breakdown characteristics.

• Korean Journal of Pharmacognosy
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• v.22 no.1
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• pp.36-44
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• 1991

This study was attempted to investigate the acute toxicity of Liocolae vermiculus(Liocola brevitarsis) extract in mice, the effect on GOT, GPT Al.p, LDH activities and level of total cholesterol in serum of $CCl_4-intoxicated$ rats. In acute toxicity test, Liocolae vermiculus extract showed 10% mortality at 2,000 mg/kg, p.o. and at 1,000 mg/kg, i.p.. The Liocolae verculus extract caused a remarkable decrease in serum transaminase as well as Al.p activities in $CCl_4-intoxicated$ rats at $300{\sim}1,000{\;}mg/kg$ dosage ranges. The activities of -LDH and the level of total cholesterol were significantly decreased in all sample-treated group, when compared with the control group. The body weight decreased, and the liver and spleen weight increased in $CCl_4-intoxicated$ rats were significantly recovered by the administration of the extracts.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.295-298
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• 1999

AlGaAs/InGaAs power P-HEMTS (Pseudo-morphic High Electron Mobility Transistors) with 1.0-${\mu}{\textrm}{m}$ gate length for PCS applications have been fabricated. We adopted single heterojunction P-HEMT structure with two Si-delta doped layer to obtain higher current density. It exhibits a maximum current density of 512㎃/mm, an extrinsic transconductance of 259mS/mm, and a gate to drain breakdown voltage of 12.0V, respectively. The device exhibits a power density of 657㎽/mm, a maximum power added efficiency of 42.1%, a linear power gain of 9.85㏈ respectively at a drain bias of 6.0V, gate bias of 0.6V and an operation frequency of 1.765㎓.

• Korean Journal of Plant Tissue Culture
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• v.25 no.3
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• pp.147-152
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• 1998

AL1-gene, necessary for the replication of the genome of a gemini virus TGMV, was inserted in the opposite direction to the promoter CaMV35S resulting in the construction of a plant transformation binary vector pAR35-2. The vector pAR35-2 contains the chimeric gene cassette involving the duplicated promoter CaMV35S, opposite direction of AL1-gene fusioned with hygromycin resistant gene, and the gene cassette of the neomycin phosphotransferase II gene. The plasmid was transferred to tobacco and tomato plants by leaf disk infection via Agrobacterium. The transgenic plants were selected and grown on the MS-agar medium containing kanamycin and hygromycin. The shoots induced from the calli were regenerated to the whole transgenic plants. The antisense AL1-gene was detected in the genomic DNA isolated from the leaves by using the PCR mediated Southern blot analysis. The expression of the antisense AL1-gene was also observed using the RT-PCR mediated Southern blot analysis. The observation of chloroplasts in guard cell pair indicated that the transgenic tomato plants were diploid.

• Journal of Life Science
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• v.11 no.2
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• pp.153-158
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• 2001

To investigate the effects of soil acidification on growth of Impatiens balsamina L. plants were transplanted to acidified soils with H$_2$SO$_4$ solution. The concentrations of soluble Ca, Mg, K, Al and Mn in the acidified soils increased with increment of H$^{+}$ addition to the soil. In both species, the plant height and root length were inhibited by soil acidification, showing much severer inhibition in Impatiens balsamina L. than in Tagetes patula L., As the soil pH decreases, the growth of underground parts decreased greatly than that of above ground parts in both species. Total dry weight decreased with increased Al concentration as well as lowered soil pH in both plants. There was a strong positive correlation between relative total dry weight and molar (Ca+Mg+K) / Al ratio of the soil. The results suggest that molar(Ca+Mg+K)/ Al ratio of the soil may be useful indicator for assessing the critical load of acid deposition in herb species.s.