• Transactions on Electrical and Electronic Materials
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• v.10 no.1
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• pp.5-8
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• 2009

The reliability of multilayer ceramic capacitor with active thin dielectric layer was investigated by highly accelerated life test at various stress condition. The distribution of multilayer ceramic capacitor failure times is plotted as a function of time from Weibull distribution function. According to the test result, voltage acceleration factor is obtained from 2.24 to 2.96. The acceleration by temperature is much higher than other values of active thick dielectric layer. It is clear that median time to failure is affected by the stress voltage for high volumetric efficiency ceramic capacitors with active thin dielectric layer. The degradation under stress of voltage involves electromigration and accumulation of oxygen vacancy at Ni electrode interface of cathode.

• Corrosion Science and Technology
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• v.12 no.4
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• pp.163-170
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• 2013

In NaCl solutions acidified with $H_2SO_4$, Fe20Cr1.1N alloy showed enhanced pitting corrosion resistance than Fe20Cr alloy. An XPS analysis revealed that the passive film of Fe20Cr1.1N alloy contained higher cationfraction of Cr than that of Fe20Cr alloy, and nitrogen was incorporated into the film. In addition, it was found that the passive film of Fe20Cr1.1N alloy was thinner and had higher oxygen vacancy density than that of Fe20Cr alloy. Based on these observations, it was concluded that the chemical composition was the determining factor for the protectiveness of the passive film of Fe20Cr based alloy in dilute $H_2SO_4$ solution.

• ETRI Journal
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• v.34 no.2
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• pp.280-283
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• 2012

By inserting $H_2O$ treatment steps during atomic layer deposition of a ZnO layer, the turn-on voltage shift from negative bias stress (NBS) under illumination was reduced considerably compared to that of a device that has a continuously grown ZnO layer without any treatment steps. Meanwhile, treatment steps without introducing reactive gases, and simply staying under a low working pressure, aggravated the instability under illuminated NBS due to an increase of oxygen vacancy concentration in the ZnO layer. From the experiment results, additional oxidation of the ZnO channel layer is proven to be effective in improving the stability against illuminated NBS.

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.251-256
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• 2011

The luminescence properties of polycrystalline ZnO annealed in reducing ambience ($H_2/N_2$) have been studied. An effective quenching of green luminescence with enhanced UV emission from polycrystalline ZnO is observed for the reduced ZnO. The variations of the UV and green luminescence band upon reduction treatment are investigated as a function of temperature in the range between 20 and 300 K. Upon annealing treatment in reducing ambience, the optical quality of polycrystalline ZnO is improved. The UV to green intensity ratio of sintered ZnO approaches close to zero (~0.05). However, this ratio reaches more than 13 at room temperature for polycrystalline ZnO annealed at $800^{\circ}C$ in reducing ambience. Furthermore, the full width at half maximum (FWHM) of the UV band of polycrystalline ZnO is reduced compared to unannealed polycrystalline ZnO. Electron paramagnetic resonance (EPR) measurements clearly show that there is no direct correlation between the green luminescence and oxygen vacancy concentration for reduced polycrystalline ZnO.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.908-911
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• 1995

The EPR spectra of Cu-or Zr-doped BaTiO3 ceramics exhibited absorption signals with g∥=2.380 and g⊥=2.063 which are assigned to Ba1+(Ba2+ + e'→Ba1+) ion reduced by an electron that was produced from the oxygen vacancy (VO..). The intensity of these signals decreased as the temperature increased indicating that Ba1+ was changed to Ba2+ as the temperature increased. These ceramics also showed the EPR signal with g=1.997 around TC which arises from ionized Ba-vacancies, VBa'(VBa + e'→VBa'. In the orthorhombic and tetragonal phase region g=1.997 signal was not seen. The electrons generating from the oxidation of Ba1+ and ionized Ba-vacancies may contribute to a space charge which is responsible for a dielectric relaxation of these samples.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.2
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• pp.147-150
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• 2019

There is a need for the development of transparent conductive materials that are economical and environmentally friendly with exhibit low resistivity and high transmittance in the visible spectrum. In this study, the deposition rate and uniformity of Al-doped ZnO-thin films were improved by changing the Z-motion of the sputtering system. The deposition rate and the uniformity were determined to be 3.44 nm/min and 1.23%, respectively, under the 10 mm Z-motion condition. During $O_2$ plasma treatment, the intrusion-type metal elements in the thin film were reduced, which contributed to an oxygen vacancy reduction in addition to structural stabilization. Moreover, the sheet resistance was more easily saturated.

• Journal of the Korean Chemical Society
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• v.8 no.2
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• pp.68-74
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• 1964

Water has the melting point, the boiling point, the heat of fusion, and the heat of vaporization all much higher than would be normally expected from the hydrogen compounds of the other members of the oxygen family. Another unique characteristic of ice-Ⅰ is its volume decrease which takes place in its melting. A number of significant efforts have been made in the past to explain these properties quantitatively. The authors, reasoning from the unusually great free surface energy of water and the characteristic volume change on melting, propose the structural model of liquid water as follows. On melting, fluidized vacancies of a molecular size are introduced. Thereupon, for the unusually great surface energy density, molecules surrounding the vacancies become to have close packed arrangement. But molecules not in direct contact with vacancies should still possess the original structure i. e., ice-Ⅰ. When a molecule adjacent to a vacancy jumps into the vacancy, the molecule attains the gaslike degree of freedom. Using the above model, the authors had developed the liquid partition function of water by applying the theory of significant structures in liquids. Molar volume, vapor pressure, entropy of fusion and entropy of vaporization were calculated over a wide temperature range. The results show good agreement with experimental observations.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.60.2-60.2
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• 2011

본 연구에서는 Indium-free 및 gallium-free 기반의 산화물 TFT를 제작하기 위해 n-type $TiO_2$ 반도체 기반의 thin film transistor ($Mo/TiO_{2-x}/SiO_2/p+\;+Si$)를 oxygen deficient black $TiO_{2-x}$ 타겟을 이용하여 DC magnetron sputtering 공법으로 제작하고 그 특성을 분석하였다. DC magnetron sputtering 공법으로 성막된 $TiO_{2-x}$ semiconductor의 전기적, 광학적, 화학적 결합 에너지 및 구조적 특성 분석을 위해 semiconductor parameter analyzer (Aglient 4156-C), UV/Vis spectrometer, X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy를 각각 이용하여 분석하였으며 이를 RTA 전/후 특성 비교를 통하여 관찰하였다. $TiO_{2-x}$ TFT의 소자 특성은 RTA 열처리 전/후 전형적인 insulator 특성에서 semiconductor 특성으로 변화되는 것을 관찰할 수 있었으며, 최적화된 열처리 공정에서 filed effect mobility 0.69 $cm^2$/Vs, on to off current ratio $2.04{\times}10^7$, sub-threshold swing 2.45 V/decade와 Vth 10.45 V를 확보할 수 있었다. 또한 RTA 열처리 후 밴드갭이 3.25에서 3.41로 확장되는 특성을 나타내었다. 특히 RTA 열처리 후 stoichiometric $TiO_2$ 상태와는 다른 $Ti^{2+}$, $Ti^{3+}$, $Ti^{4+}$ 등의 다양한 oxidation states가 관찰되었으며 이러한 oxidation states를 $TiO_{2-x}$ 박막에서의 oxygen deficient 상태와 연관시킴으로써 oxygen vacancy의 n-type dopant로의 거동을 확인하였다. $TiO_2$ 채널 기반의 TFT 특성을 통하여서 indium free 또는 gallium free 산화물 채널로써의 가능성을 확인하였다.

• Applied Microscopy
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• v.32 no.3
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• pp.257-263
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• 2002

Microstructural investigations of $(Li_{1/2}Pr_{1/2})TiO_3$ (LPT) complex perovskite compounds were carried out using X-ray diffractometry and transmission electron microscopy. LPT has not only the ordering of A-site cation deficiencies but also has the antiphase and inphase tilting of oxygen octahedron and the antiparallel shift of cations. Both the antiphase boundaries and the ferroelastic domains are present in the microstructure. Spinodal decomposition is found in the microstructure. The measured dielectric properties were ${\varepsilon}_r=84.6,\;Q\;{\Large f}_o=776\;GHz,\;{\tau}_{f}=-233.66ppm/^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.33-39
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• 1986

The x-values of nonstoichiometry chemical formulas, Sm$O_{1.5+x}$ and Zr$O_{2+x}$, have been measured in temperature range from 500$^{\circ}$C to 1000$^{\circ}$C under oxygen pressure of 2 ${\times}10^{-1}$ to 1 ${\times}10^{-5}$ atm by gravimetric method. The enthalpies of formation of defect in samarium sesquioxide and zirconium dioxide decrease with decreasing oxygen pressure and are all positive. The 1/n values calculated from the slopes of the plots of log x vs. log $PO_2$ increase with temperature and are positive values which mean the higher oxygen pressure dependence at higher temperature. From x-values and thermodynamic data, it is found out that the nonstoichiometric defect is fully ionized metal vacancy. The conduction mechanisms of the systems are also discussed with respect to the nonstoichiometric compositions.