• The Korean Journal of Ceramics
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• v.2 no.1
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• pp.11-18
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• 1996

The variation of electrical conductively and Seebeck coefficient of FeSi2 according to the density of the specimen has been observed over the temperature range 50 to $700^{\circ}C$. A conventional pressureless sintering method with various sintering time (0, 0.5, 1, 5h) at $1190^{\circ}C$ and/or various sintering temperatures(1160, 1175, 1190, $1200^{\circ}C$) for 2 h was carried out to prepare $FeSi_2$ specimens having various densities. The relationship between the electrical conductivity and Seebeck coefficient was investigated after two steps of annealing (at $865^{\circ}C$ and then $800^{\circ}C$ for total 160h) and thermoelectric measurement. The electrical conductivity for the specimens showed a typical tendency of semiconductor, the average activation energy of which in the intrinsic region (above $300^{\circ}C$) was observed approximately as 0.452 eV, and increased slightly with density. On the other hand, the specimen of the lower density showed the higher value of Seebeck coefficient in the intrinsic region. As the temperature fell into the non-degenerate region, the highly densified specimen which had relatively little residual metal phase showed the higher value of Seeback coefficient. The power factor of all specimens showed the optimum value at $200^{\circ}C$. However, the power factor of the specimen of the lower density increased again from $400^{\circ}C$ and that of the higher dense specimen increased from $500^{\circ}C$. The power factor was more affected by Seebeck coefficient than electrical conductivity over all temperature range.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.6
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• pp.272-278
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• 2003

$Bi_4Ti_3O_{12}$ (BIT) and $(Bi_{3.25}La_{0.75})(Ti_{2.97}V_{0.03})O_{12}$ (BLTV) thin films were deposited on ITO/glass substrates by metal organic chemical vapor deposition (MOCVD) using ultrasonic spraying. After deposition of the films in oxygen atmosphere for 30 min, the films were heated by rapid thermal annealing (RTA) method, especially direct insertion, at various temperatures. The films were investigated on phase formation temperature, microstructure and electrical properties. From x-ray diffraction (XRD) patterns, the perovskite phase formation temperature of BLTV thin film was about $600^{\circ}C$ which was lower than that of BIT, $650^{\circ}C$. The leakage current of the BLTV thin film was measured to be $1.52\times 10^{-9}$A/$cm^2$ at an applied voltage of 1 V. The remanent polarization (Pr) and coercive field (Ec) values of the BLTV film deposited at $650^{\circ}C$ were $5.6\muC/cm^2$ and 96.5 kV/cm, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.371-377
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• 2003

We perform the physical analysis such that Si/W composition ratios and phosphorus distribution change in the W/S $i_{x}$ thin films according to phosphorus concentration of polysilicon and W $F_{6}$ flow rate for the formation of WS $i_{x}$ polycide used as a gate electrode. We report that these physical characteristics have effects on the contact resistance between word line and bit line in DRAM devices. RBS measurements show that for the samples having phosphorus concentrations of 4.75 and 6.0${\times}$10$^{2-}$ atoms/㎤ in polysilicon, by applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm, Si/W composition ratio has increases to 2.05∼2.24 and 2.01∼2.19, respectively. SIMS analysis give that phosphorus concentration of polysilicon for both samples have decreases after annealing, but phosphorus concentration of WS $i_{x}$ thin film has increases by applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm. The contact resistance between word line and bit line in the sample with phosphorus concentration of 6.0 ${\times}$ 10$^{20}$ atoms/㎤ in polysilicon is lower than the sample with 4.75 ${\times}$ 10$^{20}$ atoms/㎤ After applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm, the contact resistance has been improved dramatically from 10.1 to 2.3 $\mu$ $\Omega$-$\textrm{cm}^2$.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.46-53
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• 1998

A new method to form the double structured active layers of a-Si/a-SiN$_{x}$ of polycrystalline thin film transistor is proposed and poly-Si TFTs employed double structure active film are fabricated. Nitrogen ions were added to bottom amorphous silicon active film(a-SiN$_{x}$ ) and pure a-Si film deposition on a-SiN$_{x}$ was followed. The XeCl excimer laser was irradiated to crystallize double structure active film. The grain growth of upper a-Si film was also promoted in the double structured active layers of a-Si/a-SiN$_{x}$ due to the mitigation of solidification process of lower a-SiN$_{x}$ layer. Our experimental results show that the ratio of NH$_3$/SiH$_4$ is required to maintain below 0.11 for the reduction of contact resistance of n$^{+}$ poly-SiN$_{x}$ layer.r.

• Biomedical Science Letters
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• v.2 no.2
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• pp.241-247
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• 1996

Poor yields of amplified DNAs could be resulted in polymerase chain reaction(PCR) processes with G+C-rich DNA primers because of their high $T_m$ values. To maximize the yields of amplification in PCR processes with G+C-rich primers, we compared the yields of amplified DNA fragments according to the concentrations of specific denaturants added to the reaction mixture of PCR system. With addition of the mixture of 2.5% glycerol and 1.25% formamide, or 2.5% dimethyl sulfoxide to the reaction cocktail, respectively, remarkable increases in the yields of amplified DNA fragments were not observed in the PCR systems with G+C-low primers of Lyl chromosomal gene from Borrelia burgdorferi but observed in the PCR system with G+C- ich primers of Is900 gene from Mycobacterium parahberculosis. Although we were not practically able to discriminate the yields of PCR DNAs according to the concentrations used in this study, addition of the mixture of 5% glycerol and 2.5% formamide, or 5% DMSO tended to increase the production of extra bands.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.581-588
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• 2013

This paper presents a study of the process temperature dependence of $Al_2O_3$ film grown by thermal atomic layer deposition (ALD) as a passivation layer in the crystalline Si (c-Si) solar cells. The deposition rate of $Al_2O_3$ film maintained almost the same until $250^{\circ}C$, but decreased from $300^{\circ}C$. $Al_2O_3$ film deposited at $250^{\circ}C$ was found to have the highest negative fixed oxide charge density ($Q_f$) due to its O-rich condition and low hydroxyl group (-OH) density. After post-metallization annealing (PMA), $Al_2O_3$ film deposited at $250^{\circ}C$ had the lowest slow and fast interface trap density. Actually, $Al_2O_3$ film deposited at $250^{\circ}C$ showed the best passivation effects, that is, the highest excess carrier lifetime (${\tau}_{PCD}$) and lowest surface recombination velocity ($S_{eff}$) than other conditions. Therefore, $Al_2O_3$ film deposited at $250^{\circ}C$ exhibited excellent chemical and field-effect passivation properties for p-type c-Si solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.95-95
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• 2009

Single-crystalline Bi nanowires have motivated many researchers to investigate novel quasi-one-dimensional phenomena such as the wire-boundary scattering effect and quantum confinement effects due to their electron effective mass (~0.001 me). Single crystalline Bi nanowires were found to grow on as-sputtered films after thermal annealing at $270^{\circ}C$. This was facilitated by relaxation of stress between the film and the thermally oxidized Si substrate that originated from a mismatch of the thermal expansion. However, the method is known to produce relatively lower density of nanowires than that of other nanowire growth methods for device applications. In order to increase density of nanowire, we propose a method for enhancing compressive stress which is a driving force for nanowire growth. In this work, we report that the compressive stress can be controlled by modifying a substrate structure. A combination of photolithography and a reactive ion etching technique was used to fabricate patterns on a Si substrate. It was found that the nanowire density of a Bi film grown on $100{\mu}m{\times}100{\mu}m$ pattern Si substrate increased over seven times higher than that of a Bi sample grown on a normal substrate. Our results show that density of nanowire can be enhanced by sidewall effect in optimized proper pattern sizes for the Bi nanowire growth.

• Herbal Formula Science
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• v.14 no.1
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• pp.82-104
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• 2006

Objectives: The aim of this study is to find the therapeutic meaning of the Pyrite in herbal medication. Methods: About the origin, the component, the processing the drug, the properties and tastes of drugs, the meridian tropism, the effects, the treating disease, the contraindication and the method of administration. We have researched thirty three literatures to mention the pyrite in time sequence. Results: 1. The pyrite belongs to the metallic herbs and it consists of Iron sulfide, sometimes containing small amounts of cobalt, nickel. silver, and gold. 2. The processing the drug are the tempering, the annealing with vinegar. the refining drug with water or RADIX GLYCYRRHIZAE and et cetra, and accoring to these methods, the pyrite classified into three groups - the rough pyrite, the tempered pyrite, the annealed pyrite. 3. The properties and tastes of drugs is pungent and regular. If pyrite is well refine, it is nearly safe form the metallic virulence. the meridian tropism is mainly liver meridian. 4. From old times, pyrite has come into general use to treat the injury of muscles and tendons and bone facture because it is effective on dissipating blood stasis, alleviating pain and reunion of bone, muscles and ligament. 5. When the symptom is gone, a medicine to contain pyrite must be stoped taking. Because of pyrite's effect on regulateing Gi and promoting blood flow. Conclusions: This study showed that the pyrite is useful herb to treat the injury of muscles and tendons and bone facture.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.398.1-398.1
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• 2014

The $Cu_2ZnSnSe_4$ (CZTSe) thin films solar cell is one of the next generation candidates for photovoltaic materials as the absorber of thin film solar cells because it has optimal bandgap (Eg=1.0eV) and high absorption coefficient of $10^4cm^{-1}$ in the visible length region. More importantly, CZTSe consists of abundant and non-toxic elements, so researches on CZTSe thin film solar cells have been increasing significantly in recent years. CZTSe thin film has very similar structure and properties with the CIGS thin film by substituting In with Zn and Ga with Sn. In this study, As-deposited CZTSe thin films have been deposited onto soda lime glass (SLG) substrates at different deposition condition using Pulsed Laser Deposition (PLD) technique without post-annealing process. The effects of deposition conditions (deposition time, deposition temperature) onto the structural, compositional and optical properties of CZTSe thin films have been investigated, without experiencing selenization process. The XRD pattern shows that quaternary CZTSe films with a stannite single phase. The existence of (112), (204), (312), (008), (316) peaks indicates all films grew and crystallized as a stannite-type structure, which is in a good agreement with the diffraction pattern of CZTSe single crystal. All the films were observed to be polycrystalline in nature with a high (112) predominant orientation at $2{\theta}{\sim}26.8^{\circ}$. The carrier concentration, mobility, resistivity and optical band gap of CZTSe thin films depending on the deposition conditions. Average energy band gap of the CZTSe thin films is about 1.3 eV.

• Korean Journal of Materials Research
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• v.11 no.1
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• pp.55-60
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• 2001

The effect of high energy B ion implantation and initial oxygen concentration upon defect formation and gettering of metallic impurities in Czochralski silicon wafer has been studied by applying DLTS( Deep Level Transient Spectroscopy), SIMS(Secondary ton Mass Spectroscopy), BMD (Bulk Micro-Defect) analysis and TEM(Transmission Electron Microscopy). DLTS results show the signal of the deep levels not only in as-implanted samples but also in low and high temperature annealed samples. Vacancy-related deep levels in as- implanted samples were changed to metallic impurities-related deep levels with increase of annealing temperature. In the case of high temperature anneal, by showing the lower deep level concentration with increase of initial oxygen concentration, high initial oxygen concentration seems to be more effective compared with the lower initial oxygen one.