• Journal of Advanced Marine Engineering and Technology
• /
• 제33권5호
• /
• pp.637-645
• /
• 2009

The main purpose of this study lies on the improvement of micro dilution tunnel based on the typical porous tube type chamber. The characteristics of flow and temperature fields for steady state has been obtained by numerical analysis using FLUENT. Three different geometrical variations of the porous tube; a) increase of thickness at center, b) step increase of thickness at center and downstream, c) tapered increase of thickness, have been proposed. Accordingly results are obtained and compared in terms of penetration velocity and velocity ratio to therrmophoretic velocity for improvement against particulate deposition inside the tube. The penetration velocity and velocity ratio distributions in the upstream portion and portion of impinging of dilution air are apparently shown to be improved for the case of the step and tapered change of porous tube. The tapered change of tube thickness addition are shown to be the most effective among three geometrical changes. In addition, the considerable improvement against deposition are shown that its thickness should be at least 2mm.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
• /
• pp.57-57
• /
• 2003

High dielectric constant materials (high K) have attracted a great deal of interest because of the dramatic scaling down of DRAM capacitor reaching its physical limit in terms of reduction of thickness. Among high-K materials that can replace silicon dioxide, tantalum pentoxide (Ta2O5) thin film, with their high dielectric constant (∼25) and good step coverage, is the candidate of choice.

• 한국재료학회지
• /
• 제9권1호
• /
• pp.86-91
• /
• 1999

(001) $\textrm{SrTiO}_3$(STO) 기판위에 고온초전도 $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$(YBCO)박막을 이용한 계단형 모서리 임계접합을 제조하였다. STO (100) 단결정 기판위에 계단형 모서리(step-edge)를 제작하기 위한 이온밀링 마스크로 plasma enhanced chemical vapor deposition방법으로 증착된 diamond-like carbon (DLC) 박막을 사용하였고, oxygen reactive ion etch 방법으로 건식식각하였다. 이렇게 제작된 계단형 모서리 기판위에 c-축 수직한 YBCO 박막과 STO박막을 pulsed laser deposition방법으로 에피텍셜하게 증착하였다. 계단의 상층과 하층에서 모두 임계가 형성되었으며 이 접합의 임계온도는 77 K 이상이었고 16K에서 $\textrm{I}_{c}\textrm{R}_{n}$products가 7.5mV, 77 K에서 0.3mV의 값을 나타내었다. 이들 전류-전압 특성은 two noisy resistively shunted Josephson junction 모델을 잘 만족하였다.

• Progress in Superconductivity
• /
• 제2권2호
• /
• pp.71-75
• /
• 2001

The effect of annealing step-edges of LaAlO$_3$ and MgO single crystal substrates on YBa$_2$Cu$_3$O$_{7}$ junction has been studied. The step-edge was fabricated by argon ion milling and was annealed at 105$0^{\circ}C$ in 1 attn oxygen pressure. We compared AFM image near step-edge of the substrates between before and after annealing process. And YBa$_2$Cu$_3$O$_{7}$ thin film was deposited on the step-edge by a standard pulsed laser deposition. The step-edge junctions were characterized by current-voltage curves at 77 K. The annealing of step-edges of MgO substrate improved the current-voltage characteristic of Josephson junction: double steps in the current-voltage characteristic disappeared. However the annealing for LaAlO$_3$ did not improve the junction property.rty.

• 한국수소및신에너지학회논문집
• /
• 제14권1호
• /
• pp.8-16
• /
• 2003

$TiO_2$ thin films were deposited by DC reactive magnetron sputtering with variations in sputtering parameter such as Ar and $O_2$ flow rate, DC power, substrate temperature and magnetic field. Deposition rate, crystal structure, chemical bond of $TiO_2$ films on the deposition conditions were investigated by Alpha-step, X-ray Diffractometer(XRD), X-ray Photoelectron Spectroscopy(XPS). When the DC power was applied at 500watt, deposition rate of $TiO_2$ film was about 480A/min. $TiO_2$ films coated under the deposition condition of 15sccm Ar and 7~10sccm $O_2$ flow rate was only observed anatase phase. With increasing substrate temperature from RT to $300^{\circ}C$, crystal orientation of $TiO_2$ films variously became.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.207-207
• /
• 2010

휴대용 기기의 사용이 증가하면서 전지의 고용량화와 소형화가 요구되고 있다. 특히 의료용 센서 기기에서는 소형화가 매우 중요하며 인체에 해로운 물질로 구성되지 않는 것이 바람직하다. 최근 고체전해질을 사용하는 마이크로 배터리가 개발되고 있으나, 에너지 저장용량이 작아 응용분야가 제한적이다. Silicon wafer 위에 형성된 고단차의 3차원 박막 배터리를 형성한다면 표면적 증가에 의해 에너지 저장용량 역시 크게 증가할 것이다. 따라서 고단차의 3차원 구조위에 confomal한 박막을 형성하기 위해서는 기존 물리증착방법과는 달리 새로운 step coverage가 우수한 박막증착법이 필요하다. 본 연구에서는 atomic layer deposition(ALD)으로 박막 배터리의 cathode 물질인 $LiCoO_2$를 증착하기 위한 기초연구로서 cobalt oxide 박막의 ALD 공정을 연구하였다. Cobalt +2가 전구체와 $O_3$를 교대로 공급하여 박막을 증착하고 그 박막의 물리적, 화학적, 전기적 특성을 조사하였다. 이를 통해 exposure와 기판온도가 박막의 특성에 미치는 영향을 고찰하였다. 또한 pattern wafer위에 박막을 증착하여 step coverage를 조사하였다.

• 한국세라믹학회지
• /
• 제31권3호
• /
• pp.257-264
• /
• 1994

The objectives of this study were to develop the low pressure chemical vapor deposition(LPCVD) process of SiC and to fabricate pure and dense SiC layer onto graphite substrate at low temperature. The deposition experiments were performed using the MTS-H2 system (30 torr) in the deposition temperature ranging from 100$0^{\circ}C$ to 120$0^{\circ}C$. The deposition rate of SiC was increased with the temperature. The rate controlling step can be classified from calculated results of the apparent thermal activation energy as follows; surface reaction below 110$0^{\circ}C$ and gas phase diffusion through a stagnant layer over 110$0^{\circ}C$. The deposited layer was $\beta$-SiC with a preferred orientation of (111) and the strongly faceted SiC deposits were observed over 115$0^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.250-250
• /
• 2010

We have prepared CIGS thin film absorber layers with simple solution spray deposition technique and thin film were synthesized with different atomic ratio. CIGS thin films were synthesized using non-vacuum solution deposition method on pre-heated sodalime glass substrates and Mo-coated soadlime glass substrate. In precursor solution were Cu : In : Ga: S ratio 4 : 3 : 2 : 8 and the crystal type of sprayed thin film were CIGS chalcopyrite structures. This structure was identified as typical chalcopyrite tetragonal structure with XRD analysis. This result showed that CIGS solution deposition technique has potential for the one step synthesis and low cost fabrication process for CIS or CIGS thin film absorber layer.

• 한국표면공학회지
• /
• 제26권1호
• /
• pp.3-9
• /
• 1993

Chemical vapor deposited tungsten films were formed in a cold wall reactor at pressures higher (10~120torr) than those conventionally employed (<1torr). SiH4, in addition to H2, was used as the reduction gas. The effects of pressure and reaction temperature on the deposition rate and morphology of the films were ex-amined under the above conditions. No encroachment or silicon consumption was observed in the tungsten de-posited specimens. A high deposition rate of tungsten and a good step coverage of the deposited films were ob-tained at 40~80 torr and at a temperature range of $360~380^{\circ}C$. The surface roughness and the resistivity of the deposited film increased with pressure. The deposition rate of tungsten increased with the total pressure in the reaction chamber when the pressure was below 40 torr, whereas it decreased when the total pressure ex-ceedeed 40 torr. The deposition rate also showed a maximum value at $360^{\circ}C$ regardless of the gas pressure in the chamber. The results suggest that the deposition mechanism varies with pressure and temperature, the surface reac-tion determines the overall reaction rate and (2) at higher pressures(>40 torr) or temperatures(>36$0^{\circ}C$), the rate is controlled by the dtransportation rate of reactive gas molecules. It was shown from XRD analysis that WSi2 and metastable $\beta$-W were also formed in addition to W by reactions between WF6 and SiH4.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1997년도 한국재료학회 춘계학술발표회
• /
• pp.49-49
• /
• 1997