• Current Applied Physics
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• 제18권12호
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• pp.1577-1582
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• 2018

While controlling the cation contents in perovskite rare-earth nickelate thin films, a metal-to-insulator phase transition is reported. Systematic control of cation stoichiometry has been achieved by manipulating the irradiation of excimer laser in pulsed laser deposition. Two rare-earth nickelate bilayer thin-film heterostructures with the controlled cation stoichiometry (i.e. stoichiometric and Ni-excessive) have been fabricated. It is found that the Ni-excessive nickelate film is structurally less dense than the stoichiometric film, albeit both of them are epitaxial and coherent with respect to the underlying substrate. More interestingly, as a temperature decreases, a metal-to-insulator transition is only observed in the Ni-excessive nickelate films, which can be associated with the enhanced disproportionation of the Ni charge valence. Based on our theoretical results, possible origins (e.g. anti-site defects) of the low-temperature insulating state are discussed with the need of future work for deeper understanding. Our work can be utilized to realize unusual physical phenomena (e.g. metal-to-insulator phase transitions) in complex oxide films by manipulating the chemical stoichiometry in pulsed laser deposition.

• Journal of Korean Vacuum Science & Technology
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• 제6권3호
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• pp.126-132
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• 2002

The origin of image-sticking in metal-insulator-metal type thin-film diode liquid crystal displays(TFD-LCDs) is the asymmetric current-voltage(I-V) characteristic of TFD element. We developed that TFD-LCDs have reduced-image-sticking. Tantalum pentoxide(Ta$_2$O$\sub$5/) is a candidate for use in metal-insulator-metal(MIM) capacitors in switching devices for active-matrix liquid crystal displays(AM-LCDs). High quality Ta$_2$O$\sub$5/ thin films have been obtained from anodizing method. We fabricated a TFD element using Ta$_2$O$\sub$5/ films which had perfect current-voltage symmetry characteristics. We applied novel process technologies which were postannealed whole TFD element instead of conventional annealing to the fabrication. One-Time Post-Annealing(OPTA) heat treatment process was introduced to reduce the asymmetry and shift of the I-V characteristics, respectively. OPTA means that the whole layers of lower metal, insulator, and upper metal are annealed at one time. Futhermore, in this paper, we discussed the effects of top-electrode metals and annealing conditions.

• Progress in Superconductivity
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• 제11권2호
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• pp.96-99
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• 2010

We measured electrical shot noise in a metal-insulator-metal tunnel junction, which was made by using electron-beam lithography and double-angle evaporation technique. Since the dependence of the shot noise on bias voltage and temperature is theoretically well known, we can determine the temperature of the junction by measuring the noise as the voltage across the junction is changed. A cryogenic low noise amplifier was used to amplify the noise signal in the frequency range of 600-800 MHz, which enabled fast measurement of noise signal and thus temperature. With further study, this method could be useful for primary thermometry in cryogenic temperatures.

• Journal of Magnetics
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• 제16권2호
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• pp.161-163
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• 2011

We report results of first principles calculations for effects of an external electric field (E-field) on the magnetocrystalline anisotropy (MCA) in transition-metal (Fe, Co, and Ni) monolayers and at metal-insulator (Fe/MgO) interfaces by means of full-potential linearized augmented plane wave method. For the monolayers, the MCA in the Fe monolayer (but not in the Co and Ni) is modified by the E-field, and a giant modification is achieved in the $Fe_{0.75}Co_{0.25}$. For the Fe/MgO interfaces, the ideal Fe/MgO interface gives rise to a large out-of plane MCA, and a MCA modification is induced when an E-field is introduced. However, the existence of an interfacial FeO layer between the Fe layer and the MgO substrate may play a key role in demonstrating an Efield-driven MCA switching, i.e., from out-of-plane MCA to in-plane MCA.

• 한국전자파학회논문지
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• 제29권2호
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• pp.77-82
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• 2018

테라헤르츠 영역에서 MIM(Metal - Insulator - Metal) 도파관이 주기적으로 배열되어 있는 경우, 도파관 두께의 변화에 따른 전자파의 투과 특성은 널리 연구되지 않았다. 본 논문에서는 금속이 금으로 구성된 주기 구조의 경우 MIM 도파관에 수직으로 입사하는 수평 편파에 의한 전자파의 투과 특성을 다양한 테라헤르츠 주파수 영역에서 확인하고, 그 결과를 분석하고자 한다. 또한 완전 도체의 경우와 비교해 봄으로써 그 차이점을 확인한다.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.363-367
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• 2006

The structure-property relations of ternary copper chalcogenides, $TlCu_{3-x}S_2$ and $\alpha-BaCu_{2-x}S_2$ are examined. The density of states, band dispersions, and Fermi surfaces of these compounds are investigated to verify the reason of the metal-insulator transitions by extended Huckel tight-binding band calculations. The origin of the metalinsulator transitions of non-stoichiometric $TlCu_{3-x}S_2$ and $\alpha-BaCu_{2-x}S_2$ is thought to be the electronic instability induced by their Fermi surface nesting.

• 전자공학회논문지A
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• 제31A권8호
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• pp.53-61
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• 1994

Intermetallic dielectric layer was formed by using SiO$_2$/SOG/SiO$_2$ for aluminum based dual-metal interconnection process and its electric characteristics were evaluated. The dielectric layer was in the cost and facility point of view more useful than the insulator that was formed by etch-back process. The planarity by using SOG process was about 40% higher than that of the insulator by the CVD process. When SiO$_2$ films were deposited by the PECVD process the Al hillock formation during the next process was restrained bucause the intermetalic insulator was made at low temperature. The leakage current was 1${\times}10^{7}~1{\times}10^{-8}A/cm^{2}$ at the electric field of 10$^{5}$V/cm and breakdown filed was 4.5${\times}10^{6}~7{\times}10^{6}A/cm$. So we had confirmed that siloxane SOG was very useful for intermetallic layer material.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.140-142
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• 2001

In this study mechanical for stress according to Pin type of high voltage suspension type insulator. R-shaped metal pin. and a tapered metal pin having a tensile pin having a tensile strength of more than the breaking strength of insulating body are provided in porcelain insulating bodies, and a suspension insulator according to the present invention, a test for determining the tensile strength of the insulating body was made and the results. These insulators are designed and produced by using the computer analysis of mechanical and electrical stresses together with the technical know-how accumulated from long year of study into every respect of insulators.

• Current Applied Physics
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• 제18권11호
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• pp.1393-1398
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• 2018

We have investigated Bernal-stacked tetralayer graphene as a function of interlayer distance and perpendicular electric field by using density functional theory calculations. The low-energy band structure was found to be very sensitive to the interlayer distance, undergoing a metal-insulator transition. It can be attributed to the nearest-layer coupling that is more sensitive to the interlayer distance than are the next-nearest-layer couplings. Under a perpendicular electric field above a critical field, six electric-field-induced Dirac cones with mass gaps predicted in tight-binding models were confirmed, however, our density functional theory calculations demonstrate a phase transition to a quantum valley Hall insulator, contrasting to the tight-binding model prediction of an ordinary insulator.

• 한국진공학회지
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• 제20권5호
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• pp.327-332
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• 2011

ITO가 코팅된 유리 기판 위에 플라즈마 중합법으로 styrene 고분자 박막을 제작하고 상부 전극을 진공 열증착법으로 제작된 Au 박막으로 한 MIM (metal-insulator-metal) 소자를 제작하였다. 또한, 플라즈마 중합된 styrene 고분자 박막을 유기 절연박막으로 하고 진공열증착법으로 pentacene 유기반도체 박막을 제작하여 유기 MIS (metal-insulator-semiconductor) 소자를 제작하였다. 플라즈마 중합법으로 제작된 styrene (ppS; plasma polymerized styrene) 고분자 박막은 styrene 단량체(모노머) 고유의 특성을 유지하면서 고분자 박막을 형성함을 확인하였으며, 통상적인 중합법으로 제작된 고분자 박막 대비 k=3.7의 높은 유전상수 값을 보였다. MIM 및 MIS 소자의 I-V 및 C-V 측정을 통하여 ppS 고분자 박막은 전계강도 $1MVcm^{-1}$에서 전류밀도 $1{\times}10^{-8}Acm^{-2}$ 수준의 낮은 누설전류를 보이고 히스테리시스가 거의 없는 우수한 절연체 박막임이 판명되었다. 결과적으로 유기박막 트랜지스터 및 유기 메모리 등 플렉서블 유기전자소자용 절연체 박막으로의 응용이 기대된다.