• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.24-29
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• 2000

We propose a simple method to control the crystallization depth of amorphous silicon (a-Si) deposited by PECVD or LPCVD during the excimer laser annealing (ELA). Employing the new method, we have formed poly-Si/a-Si double film and fabricated a new poly-Si TFT with vertical a-Si offsets between the poly-Si channel and the source/drain of TFT without any additional photo-lithography process. The maximum leakage current of the new poly-Si TFT decreased about 80% due to the highly resistive vertical a-Si offsets which reduce the peak electric field in drain depletion region and suppress electron-hole pair generation. In ON state, current flows spreading down through broad a-Si cross-section in the vertical a-Si offsets and the current density in the drain depletion region where large electric field is applied is reduced. The stability of poly-Si TFT has been improved noticeably by suppressing trap state generation in drain region which is caused by high current density and large electric field. For example, ON current of the new TFT decreased only 7% at a stress condition where ON current of conventional TFT decreased 89%.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.326-333
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• 2004

The nanoprobe based on lithography, mainly represented by SPM based technologies, has been recognized as a potential application to fabricate the surface nanosctructures because of its operational versatility and simplicity. However, nanoprobe based on lithography itself is not suitable for mass production because it is time a consuming method and not economical for commercial applications. One solution is to fabricate a mold that will be used for mass production processes such as nanoimprint, PDMS casting, and others. The objective of this study is to fabricate the silicon stamper for PDMS casting process by a mastless fabrication technique using the combination of nano/micro machining by Nanoindenter XP and KOH wet etching. Effect of the Berkovich tip alignment on the deformation was investigated. Grooves were machined on a silicon surface, which has native oxide on it, by constant load scratch (CLS), and they were etched in KOH solutions to investigate chemical characteristics of the machined silicon surface. After the etching process, the convex structures was made because of the etch mask effect of the mechanically affected layer generated by nanoscratch. On the basis of this fact, some line patterns with convex structures were fabricated. Achieved groove and convex structures were used as a stamper for PDMS casting process.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1672-1678
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• 1989

Major problems preventing the device-quality GaAs/Si heterostructure are the lattice mismatch of about 4% and difference in thermal expansion coefficient by a factor of 2.64 between Si and GaAs. Ge is a good candidate for the buffer layer because its lattice parameter and thermal expansion coefficient are almost the same as those of GaAs. As a first step toward developing heterostructure such as GaAs/Ge/Si entirely by a home-built PAE (plasma-assisted epitaxy), Ge films have been deposited on p-type Si (100)substrate by the plasma assisted evaporation of solid Ge source. The characteristics of these Ge/Si heterostructure were determined by X-ray diffraction, SEM and Auge electron spectroscope. PAE system has been successfully applied to quality-good Ge layer on Si substrate at relatively low temperature. Furthermore, this system can remove the native oxide(SiO2) on Si substrate with in-situ cleaning procedure. Ge layer grown on Si substrate by PAE at substrate temperature of 450\ulcorner in hydrogen partial pressure of 10mTorr was expected with a good buffer layer for GaAs/Ge/Si heterostructure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.615-624
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• 2017

This study investigated the various physical and electrical effects of silicon direct bonding. Direct bonding means the joining of two wafers together without an intermediate layer. If the surfaces are flat, and made clean and smooth using HF treatment to remove the native oxide layer, they can stick together when brought into contact and form a weak bond depending on the physical forces at room temperature. An IR camera and acoustic systems were used to analyze the voids and bonding conditions in an interface layer during bonding experiments. The I-V and C-V characteristics are also reported herein. The capacitance values for a range of frequencies were measured using a LCR meter. Direct wafer bonding of silicon is a simple method to fuse two wafers together; however, it is difficult to achieve perfect bonding of the two wafers. The direct bonding technology can be used for MEMS and other applications in three-dimensional integrated circuits and special devices.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.1-8
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• 1997

The surface properties after plasma etching of TiW alloy using the chemistries of BCl$_{3}$ and SF$_{6}$ gases with varying mixing ratio have been investigated using XPS(X-ray photoelectron spectrocopy). The elements existed on the etched sampled have been extracted with BCL$_{3}$/SF$_{6}$ ratio and their chemical binding states have also been analysed. It was confirmed that the thickness of native oxide formed on the TiW films is thinner than 10nm by using Ar sputtering. At the same time, the roughness of etched surface has been esamnied using AFM (atomic force microscopy). on the basis of the basis of this results, the relations between the caanges of oxygen contents detected by XPS and the rouhness of etched surface have been discussed. And the etch rate and etched profile of Tiw films have been examined and the changes of the etch rate and etched prfile have been discussed with XPS results. From XPS results, the role of passivation layer consisted of Ti-S compound with XPS results. From XPS results, the role of passivation layer consisted of Ti-S compound has been proposed. Ti-S compound seems to make a role of passivation layer that surpresses Ti-O formation.ion.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.2
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• pp.127-132
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• 1996

Effects on feed intake, liveweight gain and economic benefits of supplementing lambs with urea molasses blocks, were studied. Forty eight crossbred lambs were divided into 6 groups and assigned randomly to grazing on native pasture (CONT) or along with supplements of Commercial ration (COM) and urea molasses blocks (UMBs) containing two levels of cement and calcium oxide as a binding agent. Analysis of variance revealed highly significant (p<0.01) differences in dry matter (DMI, g/day), crude protein (CPI, g/day) and metabolizable energy (MEI, MJ/day) intakes. Differences in liveweight gain (LWG, g/day), feed conversion ratio (FCR) and net economic benefit of supplementation were also highly variable. The intake of DM, CP and ME varied from 974 to 1002, 66-70 and 7.6-8.4 in lambs supplemented with UMBs, significantly (p<0.01) greater than 848, 52.5 and 5.6 in lambs supplemented with COM or FCR and net economic benefits (54.3; 57.8; 17.1 and 1.96; 2.4) in lambs supplemented with COM and UMB-2, were CONT or supplemented with UMB-1, UMB-3 and UMB-4 respectively. Factors responsible for differences in feed intake, liveweight gain and economic benefits, are discussed.

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.97-102
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• 1997

A medium energy ion scattering spectroscopy(ME1S) system has been developed and tested.In the MEIS system a toroidal electrostatic energy analyzer(TEA) and a two dimensional position sensitivedetector(PSD) were used. The energy resolution of MEIS system was estimated to be less than $4\times 10^{-3}$ and the overall angular resolution was less than 0.3". From the MEIS spectrum of $Ta_2O_5$(300 $\AA$)/ onSi analyzedousing 60 keV $H^+$, the energy loss factor(S.1 and depth resolution were estimated to he 42 eV/$\AA$ and 9.7 $\AA$, respectively. Also Si(100) surface was analyzed using the MEIS system. A random MElSspectrum was obtained from thc Si(100) covered with native oxide layers. At the double alignment condition, MElS spectrum showed ;i Si surface peak, a oxygen peak and a carbon peak.nd a carbon peak.

• Progress in Superconductivity
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• v.3 no.1
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• pp.49-55
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• 2001

Josephson junction arrays were fabricated by DC magnetron sputtering, self-aligning and reactive ion etching technique. The Al native oxide, formed by thermal oxidation, was used as the tunneling barrier of Nb/$Al-A1_2$$O_3$Nb trilayer. The arrays have 2,000 Josephson junctions with the area of $14\mu\textrm{m}$ $\times$ $46\mu\textrm{m}$. The gap voltages were in the range of 2.5 ~2.6 mV and the spread of critical current was $\pm$11~14%. When operated at 70~94 ㎓, the arrays generated zero-crossing steps up to 2.1~2.4 V. To improve transmission of microwave power and prevent diffusion of oxygen into Nb ground-plane while depositing $SiO_2$dielectric, we applied a plasma nitridation process to the Nb ground-plane. The microwave power was well propagated in Josephson junction arrays with nitridation. The difference in microwave transmission 7an be interpreted by the surface impedance change depending on nitridation.

• Biomedical Science Letters
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• v.26 no.2
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• pp.109-113
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• 2020

Dangyuja (Citrus maxima (Burm.) Merr.) is a native fruit of great economic importance in Jeju island in Korea. To provide experimental evidence for the antioxidant and anti-inflammation properties on extraction ethanol concentration of Dangyuja, 2 cultivars, including 30-year-old and 120-year-old were evaluated. 30-year-old Dangyuja 50%, 70% ethanol extracts had the highest polyphenol and flavonoid content, and the strongest 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity. To investigate the anti-inflammatory activity of Dangyuja ethanol extracts, we used BV-2 microglia cells and induced inflammation using lipopolysaccharide (LPS). Then, we measured levels of inflammatory mediators as nitric oxide (NO). Among the 6 extracts, 30-year-old Dangyuja 50% ethanol extracts show the highest anti-inflammatory activity. The results suggest that 30-year-old Dangyuja 50% ethanol extracts provides significant health benefits and may be used for developing new functional materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.17-18
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• 2005

실리콘 기판 위에 100nm의 선폭을 갖는 선들이 일정한 간격을 가지고 연속적으로 배열되어 있는 구조를 형성시켜 보았다. PMMA가 코팅되어 있는 실리콘 기판위에 전자빔으로 패턴을 하였고, 건식에칭을 통해 구조물을 형성한 후 원자 현미경으로 관찰하였다. 이러한 나노구조물의 구현은 전자빔 패터닝시에 전자빔이 실리콘 기판에 충돌할 때 나타나는 backward scattering과 proximity 효과 등의 영향으로 인해 pitch의 크기가 작아질수록 구현하기가 쉽지 않았다. 화합물반도체 단일 나노선 소자를 제작하여 소자의 전기적 특성을 측정할 때, 나노선 표면에 있는 자연산화막은 금속전극과 나노선 사이의 전기전도특성을 저해하는 요소로 알려져 있다. 이러한 자연산화막을 제거하기 위해 나노선을 건식에칭해 보았고, 원자현미경을 통해 에칭에 따른 나노선의 모양변화를 관찰하였다.