• 한국재료학회지
• /
• 제20권6호
• /
• pp.338-343
• /
• 2010

As an alternative to the W plug used in MOSFETs, a Cu plug with a NiSi contact using Ta / TaN as a diffusion barrier is currently being considered. Conventionally, Ni was first deposited and then NiSi was formed, followed by the barrier and Cu deposition. In this study, Ti was employed as a barrier material and simultaneous formation of the NiSi contact and Cu plug / Ti barrier was attempted. Cu(100 nm) / Ti / Ni(20 nm) with varying Ti thicknesses were deposited on a Si substrate and annealed at $4000^{\circ}C$ for 30 min. For comparison, Cu/Ti/NiSi thin films were also formed by the conventional method. Optical Microscopy (OM), Scanning Probe Microscopy (SPM), X-Ray Diffractometry (XRD), and Auger Electron Microscopy (AES) analysis were performed to characterize the inter-diffusion properties. For a Ti interlayer thicker than 50 nm, the NiSi formation was incomplete, although Cu diffusion was inhibited by the Ti barrier. For a Ti thickness of 20 nm and less, an almost stoichiometric NiSi contact along with the Cu plug and Ti barrier layers was formed. The results were comparable to that formed by the conventional method and showed that this alternative process has potential as a formation process for the Cu plug/Ti barrier/NiSi contact system.

• 한국결정성장학회지
• /
• 제8권4호
• /
• pp.544-549
• /
• 1998

$KMgCl_3$ 단결정을 Ar 분위기에서 최초로 Czochralski 방법을 사용하여 육성하였다. 원료시약 KCl과 $KMgCl_2$를 화학량론적인 혼합으로는 KMgCl3를 육성할 수 없었고 비화학량론적인 방법을 사용하여 $KMgCl_3$를 육성할 수 있었다. KCl과 MgCl2를 1:1의 비율로 혼합하여 결정을 육성하였을 때에는 $K_2MgCl_4$단결정이 육성되었다. 육성되어진 $KMgCl_3$ 단결정의 연속적 상전이점들을 확인하기 위하여 DTA, DSC 등이 열적 실험을 수행하였다. 그리고 $KMgCl_3$ 단결정이 강탄성적 성질을 가짐을 확인하였으며 고온 편광현미경을 사용하여 온도에 따른 강탄성 domain의 변화를 조사하였다. 또한 stress-strain 이력곡선의 조사를 통하여 결정내 spontaneous strain의 온도에 따른 변화를 조사하였다.

• 한국가시화정보학회지
• /
• 제14권3호
• /
• pp.51-58
• /
• 2016

New concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber at the lower end of spark plug and flame hole, in which fresh mixture gas can be put in through the flame hole without any fuel supply system. This spark plug was tested in a single cylinder engine dynamometer for different air fuel ratio to measure the fuel consumption rate, emission gases, and MBT timing. And constant volume combustion chamber was made to understand flame characteristics of spark plug. New spark plug induced fast burn compared to the conventional spark plug and its effects were increased in lean air fuel ratio. Pre-ignition chamber spark plug with 5 holes which had adjusted size was more stable and effective in combustion performance than pre-ignition chamber spark plug with 1 hole. And its effects showed larger differences in lean air fuel ratio than stoichiometric condition. Flame kernel and flame growth process of conventional spark plug and pre-ignition chamber spark plug studied by flame visualization of schlieren method.

• Progress in Superconductivity
• /
• 제9권1호
• /
• pp.91-95
• /
• 2007

[ $YBa_2Cu_3O_{7-{\delta}}$ ] films have been prepared on $LaAlO_3$ (100) single-crystal substrates by the metal organic deposition using dichloroacetate precursors (DCA-MOD). DCA precursor solutions with different composition such as; Yttrium-excess(15 at%), barium-poor(25 at%), and a stoichiometric(Y:Ba:Cu=1:2:3) were prepared in order to investigate the effects of precursor composition on the properties of YBCO films prepared by DCA-MOD method. Coated films were calcined at low temperature up to $500^{\circ}C$ in flowing humid oxygen atmosphere. Conversion heat treatment was performed $800^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. For the film prepared using excess yttrium composition, high critical current density ($J_c$) of $>2MA/cm^2$ was obtained whereas, for the films prepared using barium-poor composition, $J_c$ was lower than $1MA/cm^2$.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
• /
• pp.130-133
• /
• 2009

$Cu_2ZnSnSe_4$(CZTSe) is one of the promising materials for the solar cell due to its abundant availability in the nature. In this study, we report the fabrication of CZTSe thin film by Pulsed Laser Deposition(PLD) method using quaternary compound target on sodalime glass substrate. The quaternary CZTSe compound target was synthesized by solid state reaction method using elemental powders of Cu, Zn, Sn and Se. Powders were milled in high purity ethanol using zirconia ball with mixed size of 1 and 3 mm at the same proportions for 72 hours milling time. The structural, chemical and mechanical properties of the synthesized CZTSe powders were investigated prior to the deposition process. The CZTSe compound powder, and $500^{\circ}C$ of sintering temperature shows the best properties for PLD target. Results show that the as-deposited CZTSe thin films with the precursors by PLD have a composition near-stoichiometric.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
• /
• pp.145-146
• /
• 2006

The most Important research topic in the development of ZnO LED and LD is the production of p-type ZnO thin film that has minimal stress with outstanding stoichiometric ratio. In this study, Phosphorus diffused into the undoped ZnO thin films using the ampoule-tube method for the production of p-type znO thin films. The undoped ZnO thin films were deposited by RF magnetron sputtering system on $GaAs_{0.6}P_{0.4}$/GaP and Si wafers. 4N Phosphorus (P) was diffused into the undoped ZnO thin films in ampoule-tube which was performed and $630^{\circ}C$ during 3hr. We found the diffusion condition of the conductive ZnO films which had p-type properties with the highest mobility of above 532 $cm^2$/Vs compared with other studies PL spectra measured at 10K for the purpose of analyzing optical properties of p-type ZnO thin film showed strong PL intensity in the UV emission band around 365nm ~ 415nm and 365nm ~ 385nm.

• Journal of Magnetics
• /
• 제6권1호
• /
• pp.23-26
• /
• 2001

Nano-crystalline hexaferrite $BaFe_{12}O_{19}$(BaM) thin films have been prepared by the sol-gel method. A solution of Ba-nitrate and Fe-nitrates was dissolved in solvent with the stoichiometric ratio Ba/Fe=1/10. Films were spin-coated onto $SiO_2$Si substrates, dried and then heated in air at various temperatures. In films prepared at a drying temperature $T_d=250^{\circ}C$ and a crystallizing temperature 650${\circ}C$, single-phase BaM was obtained. High coercivities were obtained in these nano-crystalline thin films, 4~5.5 kOe for hexaferrite. Polycrystalline BaM/$SiO_2$/Si(100) thin films were characterized by Rutherford backscattering (RBS), thermogravimetry (TGA), differential thermal analysis (DTA), x-ray diffraction (XRD), and vibrating sample magnetometry (VSM), as well as Fourier transform infrared spectroscopy (FTIR). The perpendicular coercivity $H_{C\bot}$ and in-plane coercivity $H_{CII}$ after annealing at 650${\circ}C$ for 2 hours were 4766 Oe and 4480 Oe, respectively, at room temperature, under a maximum applied field of 10 kOe.

• 한국결정성장학회지
• /
• 제5권2호
• /
• pp.87-93
• /
• 1995

Floating zone법으로 strontium titanate 단결정을 육성하였다. 성장조건은 공기 분위기하에서 성장속도 3mm/hr, 상부축 회전속도 20~25rpm, 하부축 회전속도 15~20rpm이었으며 육성한 단결정은 옅은 갈색을 띄고 있었으며 투명하였고 annealing 후 색깔이 옅어짐을 확인할 수 있었다. 성장방위는 [112] 방향이었으며 XRD, EDS로 화학양론적인 조성은 $SrTiO_3$단일 결정상임을 알 수 있었다. $350^{\circ}C$, KOH용액에서 5분동안 chemical etching하여 etch pit pattern을 조사하였으며 상온하에서$350^{\circ}C$의 온도 범위에서 유전상수 값을 조사하였다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.313-313
• /
• 2012

ZnO and $SnO_2$, well-known wide direct band-gap semiconductors, have been considered as the most promising functional materials due to their highly sensitive gas sensing and excellent optical properties. ZnO/$SnO_2$ epitaxial hetrostructure exhibited unique luminescence properties in contrast with individual tetra-pod ZnO and $SnO_2$ nanostructures. Polycrystalline $SnO_2$-based samples $Zn_xSn_{1-x}O_2$(x=0, 0.01, 0.03, 0.05) were prepared by solid state reaction and eco-friendly hydrothermal techniques. Scanning electron microscopy equipped with electron dispersive x-ray spectra confirms the formation of near stoichiometric $Zn_xSn_{1-x}O_2$ nanorods of diameter ~10 nm. X-ray diffraction analysis revealed the rutile structure, except for x=0.07, which may have a small part of $Zn_2SnO_4$ as a secondary phase.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제7권2호
• /
• pp.76-84
• /
• 2002

On-line conversion estimation of enzymatic esterification reactions in solvent-free media was investigated. In principle, conversion to ester can be determined from the amount of water produced by the reaction, because water is formed as a by-product in a stoichiometric manner. In this study, we estimated the water production rate only from some measurements of relative humidity and water balances without using any analytical methods. In order to test the performance of the on-line conversion estimation, the lipase-catalyzed esterification of n-capric acid and n-decal alcohol in solvent-free media was performed whilst controlling water activity at various values. The reaction conversions estimated on-line were similar to those determined by offline gas chromatographic analysis. However, when the water activity was controlled at higher values, discrepancies between the estimated conversion values and the measured values became significant. The deviation was found to be due to the inaccurate measurement of the water content in the reaction medium during the initial stages of the reaction. Using a digital filter, we were able to improve the accuracy of the on-line conversion estimation method considerably. Despite the simplicity of this method, the on-line estimated conversions were in good agreement with the off-line measured values.