• 한국재료학회지
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• 제31권1호
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• pp.38-42
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• 2021

In this study, high temperature wetting analysis and AZ80/Ti interfacial structure observation are performed for the mixture of AZ80 and Ti, and the effect of Al on wetting in Mg alloy is examined. Both molten AZ80 and pure Mg have excellent wettability because the wet angle between molten droplets and the Ti substrate is about 10° from initial contact. Wetting angle decreases with time, and wetting phenomenon continues between droplets and substrate; the change in wetting angle does not show a significant difference when comparing AZ80-Ti and Mg-Ti. As a result of XRD of the lower surface of the AZ80-Ti sample, in addition to the Ti peak of the substrate, the peak of TiAl3, which is a Ti-Al intermetallic compound, is confirmed, and TiAl3 is generated in the Al enrichment region of the Ti substrate surface. EDS analysis is performed on the droplet tip portion of the sample section in which pure Mg droplets are dropped on the Ti substrate. Concentration of oxygen by the natural oxide film is not confirmed on the Ti surface, but oxygen is distributed at the tip of the droplet on the Mg side. Molten AZ80 and Ti-based compound phases are produced by thickening of Al in the vicinity of Ti after wetting is completed, and Al in the Mg alloy does not affect the wetting. The driving force of wetting progression is a thermite reaction that occurs between Mg and TiO2, and then Al in AZ80 thickens on the Ti substrate interface to form an intermetallic compound.

• E2M - 전기 전자와 첨단 소재
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• 제10권9호
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• pp.869-875
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• 1997

Bi based superconducting thin films were fabricated by 4-target RF magnetron sputtering using the method of controlling the on-off time. These thin films showed better crystal structures. The ratio of Cu/Bi decreased but the critical temperature increased with increasing the temperature of the substrate. High temperature phase low temperature of the substrate. High temperature phase low temperature phase and semiconducting phase can be formed by controlling the on-off time of the shutter respectively.

• 대한전자공학회논문지
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• 제26권11호
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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.

• 센서학회지
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• 제29권1호
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• pp.40-44
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• 2020

An integrated multifunctional sensor, capable of raising an early electric-fire warning, was fabricated. An arc-light, temperature, and humidity sensor was fabricated on a flexible substrate using a printed thin film of indium tin oxide. A polyethylene terephthalate (PET) substrate was used as the flexible substrate. The sensor was fabricated on a PET substrate, and its operating characteristics were tested. The operating performances of the sensor when serving as an arc-light, a temperature, and a humidity sensor were estimated to be 0.6247 Ω/W, 80.6 Ω/K, and -4.08 Ω/RH, respectively. The feasibility of the proposed fire sensor was demonstrated; it costs low and offers multiple functionalities.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.232.2-232.2
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• 2014

Since its discovery in 2004, graphene, a sp2-hybridized 2-Dimension carbon material, has drawn enormous attention. A variety of approaches have been attempted, such as epitaxial growth from silicon carbide, chemical reduction of graphene oxide and CVD. Among these approaches, the CVD process takes great attention due to its guarantee of high quality and large scale with high yield on various transition metals. After synthesis of graphene on metal substrate, the subsequent transfer process is needed to transfer graphene onto various target substrates, such as bubbling transfer, renewable epoxy transfer and wet etching transfer. However, those transfer processes are hard to control and inevitably induce defects to graphene film. Especially for wet etching transfer, the metal substrate is totally etched away, which is horrendous resources wasting, time consuming, and unsuitable for industry production. Thus, our group develops one-step process to directly grow graphene on glass substrate in plasma enhanced chemical vapor deposition (PECVD). Copper foil is used as catalyst to enhance the growth of graphene, as well as a temperature shield to provide relatively low temperature to glass substrate. The effect of growth time is reported that longer growth time will provide lower sheet resistance and higher VSG flakes. The VSG with conductivity of $800{\Omega}/sq$ and thickness of 270 nm grown on glass substrate can be obtained under 12 min growing time. The morphology is clearly showed by SEM image and Raman spectra that VSG film is composed of base layer of amorphous carbon and vertically arranged graphene flakes.

• 한국진공학회지
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• 제9권1호
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• pp.30-35
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• 2000

Indium-Tin Oxide (ITO) thin films were deposited on the commercial glass substrate by rf-magnetron sputtering. The ITO films with the thickness of 2,000~2,400 $\AA$ were prepared by changing the oxygen partial pressures of 2, 3, and 5%, as well as by changing the substrate temperature of $300^{\circ}C$ and $500^{\circ}C$. spectrophotometer, XRD, SEM, AFM, 4-point probe and Hall effect system were employed to characterize the ITO films. The optimum deposition conditions were the substrate temperature of $500^{\circ}C$ and oxygen partial pressure of 2-3%. At theses conditions, the ITO film showed the transmittance of 91%, the resistivity of $5.4\times10^{-3}\Omega$cm, the carrier concentration of $1.0\times10^{19}\textrm{cm}^{-3}$, and the carrier mobility of 150$\textrm{cm}^2$/Vsec. In XRD spectra, the (222) and (400) $In_2O_3$ planes were dominant under the optimum deposition conditions When the substrate was cleaned only by the method of ultrasonic cleaning without both pre-annealing and chemical treatment of the substrate, the ITO film exhibited the transmittance of 86%, the carrier concentration of $5.4\times10^{19}\textrm{cm}^{-3}$ and the mobility of 24$\textrm{cm}^2$/Vsec.

• 한국초전도ㆍ저온공학회논문지
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• 제10권4호
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• pp.6-8
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• 2008

$Y_{2}O_{3}$ nanodots have been deposited on top of the substrate surface using rf-sputtering method. This approach was adopted to be able to modulate the substrate surface with nanodots used as a seed for the flux pinning sites in the superconducting films. The nanodot density of $Y_{2}O_{3}$ was controlled mainly using the deposition time, rf-power, and substrate temperature. $Y_{2}O_{3}$ nanodots with ${\sim}\;50\;nm$ in diameter and ${\sim}\;3\;nm$ in height were obtained at rf-sputtering time of about 15 seconds using 400 watts of rf-power and $630^{\circ}C$ of substrate temperature. As deposition time increased up to about 30 seconds, the interconnected islands of $Y_{2}O_{3}$ nanodots formed, which can be clearly observed with AFM surface image. The substrate surface was covered entirely with $Y_{2}O_{3}$ layer above the deposition time of 60 seconds. The modulated surface morphologies and cross section analysis of deposited $Y_{2}O_{3}$ nanodots at various experimental conditions have been examined using AFM and discussed with respect to the flux pinning sites for the practical application.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1792-1794
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• 1999

PVDF(Polyvinylidene Fluoride) thin films were prepared by using a physical vapor deposition system. Thin films were studied by X-ray diffraction (XRD), differential scanning calorimeter (DSC). The melting point$(T_m)$ of PVDF thin films increases with increasing substrate temperature. It is found that the degree of crystallinity of PVDF thin films increases from 49.8 to 67% with increasing substrate temperature from 30 to $80^{\circ}C$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1174-1177
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• 1995

In this paper, electrical properties CdS/CdTe heterojunction solar cell prepared by electron beam evaporation method were investigated. Crystal structure of CdS films deposited at substrate temperature of $50{\sim}250^{\circ}C$ was hexagonal type with preferential orientation of the (002)plane parallel to the substrate. Optical transmittance of the CdS film is increasing and resistivity is decreasing with increasing subsrate temperature. CdS/CdTe Solar cell characteristics were improved by increasing of substrate and annealing temperature. However, low efficiency due to small Jsc, Voc below 0.3 $mA/cm^2$ and 430 mV are observed. Low efficiency is contributed to be high resistance of CdTe films and contact.

• 한국세라믹학회지
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• 제31권8호
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• pp.886-892
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• 1994

Structural and electrical properties of BaTiO3 thin films deposited on Pt/SiO2/Si substrates by RF magnetron sputtering method have been investigated. Crystallization behavior and electrical properties were studied for the films deposited under various sputtering gas compositions (Ar+O2 gas mixture) and substrate temperatures. All the films deposited above 50$0^{\circ}C$ were all crystallized and their preferred orientation changed from (001) to (111) with the addition of oxygen gas. The dielectric constant of films deposited in pure argon was about 110 and showed little dependence on the substrate temperature. But that was increased as the ratio of O2/Ar increased and its substrate temperature dependence was discernible. The highest dielectric constant reached to 550. In addition, the films deposited in mixed gas showed stable dielectric properties against the frequency and temperature.