• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.212-217
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• 2000

Bi$_2$Sr$_2$CuO$_{x}$(Bi-2201) thin films have been fabricated by atomic layer-by-layer deposition using ion beam sputtering(IBS) process. During the deposition, 14 wt%-ozone/oxygen mixture gas of typical pressure of 5.0$\times$10$^{-5}$ Torr is supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal that a buffer layer with compositions different from Bi-2201 is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.n.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.529-530
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• 2006

$Bi_2Sr_2CuO_x$ thin films have been fabricated by atomic layer-by-layer deposition using the ion beam sputtering method. During the deposition, 10 and 90 wt%-ozone/oxygen mixture gas of typical pressure of $1{\sim}9{\times}10^{-5}\;Torr$ are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• 한국정보통신학회논문지
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• 제13권1호
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• pp.115-120
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• 2009

PLD 법으로 3 wt.% Al이 도핑된 ZnO 타겟을 이용하여 corning 1737 기판위에 200 mTorr의 고정된 산소 분압에서 기판온도 ($100\;{\sim}\;250^{\circ}C$)에 따른 AZO 박막의 구조적, 광학적, 전기적 특성을 조사하였다. 모든 박막들은 c 축 배향되었으며, 오직 (002) 회절 피크만 관찰되었다. $250^{\circ}C$에서 제작한 AZO 박막에서 가장 우수한 (002) 배향성을 보였으며, 이때의 반가폭 값은 $0.44^{\circ}$ 였다. 모든 박막이 가시광 영역에서 85 % 이상의 투과율을 보였으며, Burstein-Moss 효과가 관찰되었다. 전기적 특성은 $250^{\circ}C$에서 제작한 박막에서 가장 우수한 캐리어 농도 ($3.48{\times}10^{20}cm^{-3}$)와 비저항 ($1.65{\times}10^{-2}{\Omega}cm$) 값을 나타냈다.

• 한국초전도ㆍ저온공학회논문지
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• 제26권1호
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• pp.14-19
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• 2024

In this study, we explore the anisotropy of electron-phonon coupling (EPC) constant in epitaxially grown MgB₂ films on c-axis oriented Al₂O₃, examining its correlation with the critical temperature (T_c) and local structural disorder assessed through polarized Raman scattering. Analysis of the polarized Raman spectra reveals angle-dependent variations in the intensity of the phonon spectra. The Raman active mode originating from the boron plane, along with two additional phonon modes from the phonon density of states (PDOS) induced by lattice distortion, was distinctly observed. Persistent impurity scattering, likely attributed to oxygen diffusion, was noted at consistent frequencies across all measurement angles. The EPC values derived from the primary Raman active phonon do not significantly vary with changing observation angles, followed by that the T_c values calculated using the Allen and Dynes formula remain relatively constant across all polarization angles. Although the E_2g phonon mode plays a crucial role in the EPC mechanism, the determination of T_c values in MgB₂ involves not only electron-E_2g coupling but also contributions from other phonon modes.

• 한국재료학회지
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• 제20권12호
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• pp.629-635
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• 2010

Abstract In this study characteristics of Al-doped ZnO thin film by HIPIMS (High power impulse sputtering) are discussed. Deposition speed of HIPIMS with conventional balanced magnetic field is measured at about 3 nm/min, which is 30% of that of conventional RF sputtering process with the same working pressure. To generate additional magnetic flux and increase sputtering speed, electromagnetic coil is mounted at the back side of target. Under unbalanced magnetic flux from electromagnet with 1.5A coil current, deposition speed of AZO thin film is increased from 3 nm/min to 4.4 nm/min. This new value originates from the decline of particles near target surface due to the local magnetic flux going toward substrate from electromagnet. AZO film sputtered by HIPIMS process shows very smooth and dense film surface for which surface roughness is measured from 0.4 nm to 1 nm. There are no voids or defects in morphology of AZO films with varying of magnetic field. When coil current is increased from 0A to 1A, transmittance of AZO thin film decreases from 80% to 77%. Specific resistance is measured at about $2.9{\times}10-2\Omega{\cdot}cm$. AZO film shows C-axis oriented structure and its grain size is calculated at about 5.3 nm, which is lower than grain size in conventional sputtering.

• 전자공학회논문지D
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• 제35D권4호
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• pp.93-100
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• 1998

Pyoelectric infrared detectors based on La-modified PbTiO3 (PLT) thin films have been fabricated by RF magnetron sputtering and micromachining technology. The detectors form Pb$_{1-x}$ La$_{x}$Ti$_{1-x}$ O$_{3}$ (x=0.05) thin film ferroelectric capacitors epitaxially grown by RF magnetron sputtering on Pt/MgO (100) substrate. The sputtered PLT thin film exhibits highly c-axis oriented crystal struture that no poling trealization for sensing applications is required. This is an essential factor to increase the yield for realization of an infrared image sensor. Micromachining technology is used to lower the thermal mass of the detector by giving maximum sensor efficiency. Polyimide is coated on top of the sensing elements to support the fragile structure and the backside of the MgO substrate is selectively eteched to reduce the heat loss. The sensing element exhibited a very high detectivity D* of 8.5*10$^{8}$ cm..root.Hz/W at room temperature and it is about 100 times higher than the case of micromachining technology is not used. a sensing system that detects the position as well as the existence of a human body is realized using the array sensor.sor.

• 한국표면공학회지
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• 제39권6호
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• pp.250-254
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• 2006

Effect of hydrogen partial pressure ratio on the structural and electrical properties of highly c-axis oriented ZnO films deposited by oxygen ion-assisted pulsed filtered vacuum arc at a room temperature was investigated. The hydrogen partial pressure ratio were $1.4%\sim9.8%$ at 40% oxygen pressure ratio. The conductivity of ZnO:H films was increased from 1.4% up to 4.2% due to relatively high carrier mobility caused by improvement of crystallinity While the conductivity of ZnO:H films were decreased over than 4.2% and (0002) orientation was also deteriorated. The lowest resistivity of ZnO:H films was $2.5{\times}10^{-3}\;{\Omega}{\cdot}cm$ at 4.2% of hydrogen pressure ratio. Transmittance of ZnO:H films in visible range was 85% which is lower than that of undoped ZnO films because of declined preferred orientation.

• 한국전기전자재료학회논문지
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• 제12권1호
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• pp.56-61
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• 1999

Highly conductive oxide films of BaRuO$_3$ have been grown heteroepitaxially on (100) LaAlO$_3$ single crystalline substrates by using pulsed laser deposition. The films are c-axis oriented with an in-plane epitaxial relationship of <010><100>BaRuO$_3$ // <110>LaAlO$_3$. Atomic force microscopy (AFM) observation shows that they consist of a fine-arranged network of grains and have a mosaic microstructure. Generally temperature-dependent resistivity shows the transition from metallic curve to semiconductor-metallic twofold curve by the deposition conditions for Ru oxide based materials like SrRuO$_3$, CaRuO$_3$, BaRuO$_3$, etc.. This twofold curve comes from the structural similarity of Ru oxide based materials including BaRuO$_3$. We find that the distance of Ru-Ru bonding in the unit cell of BaRuO$_3$ as well as the grain boundary scattering could be the two important causes of these interesting conductive properties.

• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.41-44
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• 2021

We developed an optimization process of the pulsed laser deposition method to grow epitaxial CeCoIn₅ thin films on MgF₂ substrates. The effects of different deposition parameters on film growth were extensively studied by analyzing the measured X-ray diffraction patterns. All the deposited films contained small amounts of CeIn₃ impurity phase and misoriented CeCoIn₅, for which the c-axis of the unit cell is perpendicular to the normal vector of the substrate surface. The deposition temperature, target composition, laser energy density, and repetition rate were found effective in the formation of (00l)-oriented CeCoIn₅ as well as the undesired phases such as CeIn₃, misoriented CeCoIn₅ along the (112) and (h00). Our results provide a set of deposition parameters that produce high-quality epitaxial CeCoIn₅ thin films with sufficiently low amounts of impurity phases and can serve as a reference for future studies to optimize the deposition process further.

• 한국세라믹학회지
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• 제41권2호
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• pp.136-142
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• 2004

출발물질로 zinc acetate dihydrate(Zn($CH_3$COO)$_2$$.$2$H_2O$)를 사용하였고, 이 물질을 isopropanol(($CH_3$)$_2$CHOH)-monoethanolamine(MEA:H$_2$NCH$_2$C$H_2O$H) 용액에 용해하여 균일하고 안정한 sol을 만들었다. Sol-gel spin-coating 법에 의해 ZnO 박막을 제조시 예열 온도에 따른 박막의 c-축 배향성과 그 물리적 특성을 조사하였다. c-축으로의 성장은 예열 온도의 변화에 따라 차이를 보였으며. 275$^{\circ}C$에서 예열 후 $650^{\circ}C$에서 최종 열처리한 ZnO 박막은 XRD 측정결과 기판에 수직한 (002) 방향으로 강한 배향성을 나타내었다 200∼30$0^{\circ}C$에서 예열 후, $650^{\circ}C$에서 최종 열처리한 ZnO 박막은 UV-vis측정결과 가시광선 영역에서 온도에 따른 투과도의 변화를 보이지만 평균 85% 이상의 높은 투과도를 보였다. 또한 370nm 부근에서 흡수단을 나타내었으며, 광학적 밴드갭은 약 3.22 eV로 나타났다. 발광방출(PL) 측정결과, 황색(620nm, 2.0 eV)발광이 관찰되어, 무기발광 소자로의 응용 가능성을 나타내었다.