• Progress in Superconductivity and Cryogenics
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• 제23권2호
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• pp.10-13
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• 2021

Superconductor-ferromagnet thin film heterostructure is an ideal system for studying the interplay between superconductivity and ferromagnetism. These two antagonistic properties combined in thin film heterostructure create interesting proximity effects such as spin-triplet superconductivity. Thin film heterostructure of optimally doped La_2-xSr_xCuO₄(LSCO) cuprate superconductor and SrRuO₃(SRO) ruthenate ferromagnet has been grown by pulsed laser deposition. Its temperature-dependent resistivity and Hall effect measurements show that our LSCO/SRO heterostructure has both superconductivity and ferromagnetism. In the Hall effect measurement results, we find additional hump-like structures appear in the anomalous Hall effect signal in the vicinity of superconducting transition. We conclude that giant magnetoresistance of the LSCO layer distorts the AHE signal, which results in a hump-like structure.

• Progress in Superconductivity and Cryogenics
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• 제6권4호
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• pp.9-12
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• 2004

We report a successful fabrication of high-$J_C$ $NdBa_2Cu_3O_{7-{\delta}}$ (NdBCO) films on (100) $SrTiO_3$ substrates by pulsed laser deposition (PLD) in high oxygen pressures ranging from 400 to 800 mTorr. Fabricated NdBCO films exhibited only c-axis orientation, good out-of-plane and in-plane textures, and also excellent superconducting properties, including critical temperature ($T_C$) and critical current density ($J_C$) of above 90 K and the highest of $3.1MA/cm^2$ at 77 K in self-field, implying that NdBCO is a perspective alternative to YBCO for coated conductor. In low oxygen pressures ranging from 100 to 200 mTorr, however, the films showed a-, c-mixed orientation and degraded $T_{C,zero}$ values due to the formation of $Nd_{1+x}Ba_{2-x}Cu_3O_{7-{\delta}}$-type solid solutions with an excessive substitution of $Nd^{3+}$ ions for the $Ba^{2+}$ sites.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.120-120
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• 2008

We demonstrate epitaxial growth of ZnO thin films on 4H-SiC(0001) substrates using pulsed laser deposition (PLD). ZnO and SiC have attracted attention for their special material properties as wide band gap semiconductors. Especially, ZnO could be applied to optoelectronic applications such as light emitting devices and photo detectors due to its direct wide bandgap (Eg) of ~3.37eV and large exciton binding energy of ~60meV. SiC shows a good lattice matching to ZnO compared with other commonly used substrates and in this regard SiC is a good candidate as a substrate for ZnO. In this work, ZnO thin films were grown on 4H-SiC(0001) substrates by PLD using an Nd:YAG laser with a 355nm wavelength. The crystalline properties of the films were evaluated by x-ray diffraction (XRD) $\theta-2\theta$, rocking curve and pole figure measurements using a high-resolution diffractometer. The surface morphology of the films was studied by atomic force microscopy (AFM).

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.86.1-86.1
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• 2010

Cu2ZnSnSe4는 CIS 태양전지의 In 대체 물질계로 주목을 받고 있는 저가형 태양전지 재료로 장차 차세대 태양전지 재료로 응용이 기대되고 있다. 그러나 에너지 밴드갭이 0.9~1.1eV로 다소 낮아 태양전지 광흡수층 재료로 사용하기 위해서는 wide band gab화 처리가 필요하다. 본 연구에서는 CZTSe에 S를 첨가하여 에너지 밴드갭을 확장하고자 하며, S의 첨가가 CZTSe 박막의 특성에 미치는 영향에 대하여 조사하였다. 실험의 편의성을 도모하고자 펄스레이저 법을 사용하여 증착하였다. 박막 조성 제어에는 Cu, Zn, Sn, Se, S 분말을 볼밀로 분쇄, 혼합하여 균질 혼합상 프리커서를 제조하고 이를 Cold Isostatic Press(CIP) 성형하여 Source target을 사용하였다. Pulsed YAG-Laser를 사용하여 soda lime glass상에 증착하고 조성, 구조, 조직을 관찰하고 에너지 밴드갭, 광흡수계수, 면저항, 전하밀도 등 특성을 조사하였다.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.288-290
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• 1997

Pulsed laser ablation has been used to fabricate superconducting $YBa_2Cu_3O_{7-x}$(YBCO) thin films on MgO substrates. The epitaxial YBCO thin films were grown at $750^{\circ}C$ and oxygen partial pressure of 200 mTorr. The electrical property and the characteristics of the YBCO thin films have been studied by R-T measurement. scanning electron microscopy (SEM) and X-ray diffraction (XRD). A microstrip line resonator has been fabricated using YBCO superconducting thin films by photolithography and wet-etch process. The resonator has linear microstrip line separated by a gap of 0.278 mm. We observed a fundamental resonance peak at the frequency of 10.007 GHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제13권1호
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• pp.28-32
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• 2000

Structural and electrical properties of (Ba, Sr)TiO\ulcorner (BST) thin films prepared by pulsed laser depositon were investigated to verify the influences of post-annealing in oxygen ambient. Increase of post-anneal-ing time in oxygen ambient resulted in not only grain growth but also improvement of crystallinity of BST films. Although the post-annealing in oxygen ambient resulted in the increase of surface roughness, it assisted the dielectric constant increase by eliminating oxygen vacancies. The electrical property enhancement including high dielectric constant and low leakage current density was associated with introducing high pressure of oxygen during the post-annealing.

• The Transactions of the Korean Institute of Electrical Engineers C
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• 제49권2호
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• pp.103-106
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• 2000

ZnO is a wide-bandgap II-IV semiconductor and has a variety of potnetial applications. ZnO exhibits good piezoelectric, photoelectric and optical properties, and is a good candidate for an electroluminescence device. ZnO films have been deposited on (001) sapphire by PLD technique. Nd:YAG pulsed laser was operated at a wavelength of $\lambda=355nm$. The ZnO films were deposited at oxygen pressures from base to 500 mTorr. The substrate temperatures was increased from $200^{\circ}C\; to\;700^{\circ}C$ films showed strong UV emission by increasing the partial oxygen pressure. We have investigated the relationship between partial oxygen pressure and the intensity of UV emission.

• Proceedings of the Korea Crystallographic Association Conference
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• 한국결정학회 2003년도 춘계학술연구발표회
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• pp.6-6
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• 2003

Highly crystalline 5H-polytypic form of sp3-bonded boron nitride (BN) was grown by pulsed-laser-vaporization of BN, where synchronous reactive-plasma packets assisted the crystal growth in the vapor phase. The structure of the product crystallites (˙5 micrometers) was confirmed by using transmission electron diffraction and electron energy loss spectroscopy. This material proved to have a sharp and dominant band at 225 nm by cathode luminescence at room temperatures and corresponding monochromatic images revealed that they uniformly emitted the ultraviolet light. Considering that cubic BN has already been doped as p- and n- type semiconductors, this material may be applied to the light-emitting devices working at almost the deepest limit of the UV region that is functional without vacuum.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.139-142
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• 1998

PLZT thin films were fabricated with different Zr/Ti ratios by pulsed laser deposition. PLZT films deposited on Pt/Ti/SiO$_2$/Si substrate. This PLZT thin films of 5000${\AA}$. thickness were crystallized at 600$^{\circ}C$, 200 mTorr O$_2$ press. 2/55/45 PLZT thin film showed a maximum dielectric constant value of $\varepsilon$$\_$r/=1500, and dielectric loss was 0.O$_3$. At 2/70/30 PLZT thin film, Coercive field and remnant polarization was respectively 19[kV/cm], 8[${\mu}$C/$\textrm{cm}^2$].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.278-281
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• 1999

PLZT thin films on Pt/Ti/SiO$_2$/Si substrate were fabricated with different Thickness by pulsed laser deposition. 14/50/50 PLZT thin film showed a maximum dielectric constant value of $\varepsilon$$_{t}$=985 at 5000$\AA$, and $\varepsilon$$_{t}$=668 at 2000A. P-EI hysteresis loop of 14/50/50 PLZT thin film was slim ferroelectric. Leakage current density of 14/50/70 PLZT thin film was 10$^{-8}$ A/$\textrm{cm}^2$ at 2000$\AA$.EX>.