• The Korean Journal of Ceramics
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• 제2권2호
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• pp.111-113
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• 1996

Dielectric properties at microwave frequency region of the five-layered compound $Ba_5Nb_4O_{15}$ prepared by the conventional solid state reaction method were investigated. $Ba_5Nb_4O_{15}$ has excellent microwave dielectric characteristics; ${\varepsilon}_r$=38, Q=7500 at 10 GHz, and ${\tau}_l$=+50 ppm/K. Since this compound has a high dielectric constant, high Q and sufficiently stable characteristics, it is useful for the applications at microwave frequencies.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.741-744
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• 2002

Single phase of multicomponent oxide ZrTiO4 film could be prepared through surface sol-gel route simply by coating the mixture of 100 mM zirconium butoxide and titanium butoxide on $Pt/Ti/SiO_2Si(100)$ substrate, following pyro lysis at $450^{\circ}C$, and annealing it at 770 $^{\circ}C.$ The dielectric constant of the film was reduced as the film thickness decreased due to of the interfacial effects caused by layer/electrode and a few voids inside the multilayer. However, the dielectric property was independent of applied dc bias sweeps voltage (-2 to +2 V).The dielectric constant of bulk film, 31.9, estimated using series-connected capacitor model was independent of film thickness and frequency in the measurement range, but theoretical interfacial thickness, ti, was dependent on the frequency. It reached a saturated ti value, $6.9{\AA}$, at high frequency by extraction of some capacitance component formed at low frequency range. The dielectric constant of bulk ZrTiO4 pellet-shaped material was 33.7 and very stable with frequency promising as good applicable devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.518-519
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• 2005

We have studied the transmittance of fringe-filed switching(FFS) using a liquid crystal with positive dielectric anisotropy. Generally, FFS having positive dielectric anisotropy has less transmittance than FFS using negative dielectric anisotropy. FFS mode transmittance depends on horizontal director deformation, however fringe filed is composed of vertical and horizontal field. Vertical field in the middle of electrode suppresses the transmittance of FFS mode, especially when we use positive one. So, it is important to prevent the LC director from the effect of vertical field. We changed the splay elastic constant and checked the transmittance. The transmittance of FFS having positive dielectric anisotropy was improved. Less tilted LC directors improve the transmittance of FFS using positive dielectric anisotropy. We can improve the transmittance by using LC which have high splay elastic constant when another LC properties are equal.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.157-158
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• 2000

In this study, to get the larger drain current of the device under the same operation condition as the conventional gate dielectric SiNx thin film transistor devices, we introduced new gate dielectric $Ta_2O_5$ thin film which has high dielectric constant $({\sim}25)$ and good electrical reliabilities. For the application for the TFT device, we fabricated the $Ta_2O_5$ gate dielectric TFT on the low-temperature-transformed polycrystalline silicon thin film using the self-aligned implantation processing technology for source/drain and gate doping. The $Ta_2O_5$ gate dielectric TFT showed better electrical performance than SiNx gate dielectric TFT because of the higher dielectric constant.

• 한국재료학회지
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• 제22권7호
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• pp.342-345
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• 2012

The dielectric properties and phase transformation of poled <001>-oriented $Pb(Mg_{1/3}Nb_{2/3})O_3-x%PbTiO_3$(PMN-x%PT) single crystals with compositions of x = 20, 30, and 35 mole% are investigated for orientations both parallel and perpendicular to the [001] poling direction. An electric-field-induced monoclinic phase was observed for the initial poled PMN-30PT and PMN-35PT samples by means of high-resolution synchrotron x-ray diffraction. The monoclinic phase appears from $-25^{\circ}C$ to $100^{\circ}C$ and from $-25^{\circ}C$ to $80^{\circ}C$ for the PMN-30PT and PMN-35PT samples, respectively. The dielectric constant (${\varepsilon}$)-temperature (T) characteristics above the Curie temperature were found to be described by the equation$(1/{\varepsilon}-1/{\varepsilon}_m)^{1/n}=(T-T_m)/C$, where ${\varepsilon}_m$ is the maximum dielectric constant and $T_m$ is the temperature giving ${\varepsilon}_m$, and n and C are constants that change with the composition. The value of n was found to be 1.82 and 1.38 for 20PT and 35PT, respectively. The results of mesh scans and the temperature-dependence of the dielectric constant demonstrate that the initial monoclinic phase changes to a single domain tetragonal phase and a to paraelectric cubic phase. In the ferroelectric tetragonal phase with a single domain state, the dielectric constant measured perpendicular to the poling direction was dramatically higher than that measured in the parallel direction. A large dielectric constant implies easier polarization rotation away from the polar axis. This enhancement is believed to be related to dielectric softening close to the morphotropic phase boundary.

• 한국응용과학기술학회지
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• 제35권3호
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• pp.676-682
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• 2018

주파수 변화에 따른 에폭시 복합체의 전기적 특성을 알아보기 위하여 온도 범위 $20[^{\circ}C]$, $100[^{\circ}C]$, $140[^{\circ}C]$, 주파수 범위 30[Hz]~3[MHz] 사에서 유전율 및 유전손실을 측정하였다. 저주파 영역에서 유전분산과 유전 손실이 나타나고 있음을 확인하였다. 또한 고온 영역에서는 충진제의 영향으로 유전율이 감소하는 것을 확인하였다.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.504-510
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• 2002

Recently, thin film capacitors of high dielectric constant and low leakage current are applied to integrated devices. In this study, (Ba, Sr)$TiO_3$ (BST) thin films for low cost were prepared by Sol-Gel method. BST solution was spin-coated on Pt/$SiO_2$/Si substrate at 4,000 rpm for 10 seconds. Coating process was repeated 3 times and then sintered at $700^{\circ}C$ for 30 minutes. Structural and electrical characteristics of each specimen were analyzed by TG-DTA, SEM, fractal phenomenon, voltage-current and dielectric factor. Thickness of BST ceramics thin films are about 2,600~2,800 ${\AA}$ at depositing 3 times. Dielectric constant of thin films was decreased in 1 kHz~1 MHz. Dielectric constant and loss to frequency were 250 and 0.02 in $(Ba_{0.7}Sr_{0.3})TiO_3$ (BST3). Leakage current of BST3 was $10^{-9}\sim10^{-11}$/ A under 3 V.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.114-114
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• 2012

Metal-oxide-semiconductor field-effect transistors (MOSFETs)의 critical dimension (CD)가 sub 45 nm로 줄어듬에 따라 기존에 gate dielectric으로 사용하고 있는 SiO2에서 발생되는 high gate leakage current 때문에 새로운 high dielectric constant (k) 물질들이 연구되기 시작하였다. 여러 가지 high-k 물질 중에서, aluminum-oxide (Al2O3)는 높은 dielectric constant (~10)와 전자 터널링 barrier height (~2eV) 등을 가지기 때문에 많은 연구가 되고 있다. 그러나 Al2O3를 anisotropic한 patterning을 하기 위해 주로 사용되고 있는 halogen-based 플라즈마 식각 과정에서 나타나는 Al2O3와 하부 layer간의 낮은 식각 selectivity 뿐만 아니라 표면에 발생되는 defect, stoichiometry modification, roughness 변화 등의 많은 문제점들로 인하여 device performance가 감소하기 때문에 이를 해결하기 위한 많은 연구들이 진행중이다. 따라서 본 연구에서는 실리콘 기판위의 atomic layer deposition (ALD)로 증착된 Al2O3를 BCl3/Ar 중성빔을 이용하여 원자층 식각한 후 식각 특성을 분석해 보았다. Al2O3 표면을 BCl3로 absorption시킨 후 Ar 중성빔으로 desorption 시키는 과정에서 volatile한 aluminum-chlorides와 boron oxychloride가 형성되어 layer by layer로 제거됨을 관찰 할 수 있었다.

• 한국세라믹학회지
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• 제34권2호
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• pp.123-130
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• 1997

본 연구에서는 유전상수가 크고, 유전체 손실이 적으며, 사용온도 범위에서 정전용량 변화율(TCC : tem-perature coefficient of capacitance)이 작고, 고압에 견딜 수 있는 재료를 개발하기 위하여 중고압용 capacitance의 기본재료로써 (Sr.Pb.Ca)TiO3-xBi2O3.3TiO2 계에서 Bi2O3.3TiO2의 mol.%를 5, 6, 7, 8, 9 mol.%로 변화시켰으며, 그 결과 고용한계 함량이 6mol.%이며, 6mol.%이상에서는 침상구조의 증가에 기인하여 유전율이 다시 감소하는 경향을 보였다. dopant로써 SiO2, Nb2O3, MnO2를 선정하여 첨가한 결과, MnO2를 첨가한 것이 유전성질이 가장 우수하였으며, MnO2의 함량이 0, 0.15, 0.3, 0.45 wt.% 증가함에 따라서 유전율의 감소와 동시에, TOC특성의 급격한 향상을 가져왔다.

• Transactions on Electrical and Electronic Materials
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• 제4권1호
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• pp.15-20
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• 2003

NiCr alloys are prepared onto poly-Si/ $SiO_2$/Si substrates to replace Pt bottom electrode with a new one for integration of high dielectric constant materials. Alloys deposited at Ni and Cr power of 40 and 40 W showed optimum properties in the composition of N $i_{1.6}$C $r_{1.0}$. The grain size of films increases with increasing deposition temperature. The films deposited at 50$0^{\circ}C$ showed a severe agglomeration due to homogeneous nucleation. The NiCr alloys from the rms roughness and resistivity data showed a thermal stability independent of increasing annealing temperature. The 80 nm thick BST films deposited onto N $i_{1.6}$C $r_{1.0}$/poly-Si showed a dielectric constant of 280 and a dissipation factor of about 5 % at 100 kHz. The leakage current density of as-deposited BST films was about 5$\times$10$^{-7}$ A/$\textrm{cm}^2$ at an applied voltage of 1 V. The NiCr alloys are possible to replace Pt bottom electrode with new one to integrate f3r high dielectric constant materials.terials.