• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.861-864
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• 2002

Ferroelectric $Bi_{4-x}Nd_xTi_3O_{12}$(BNdT) thin films with the composition(x=0.75) were prepared on pt/Ti/$SiO_2$/Si(100) substrate by metal-organic deposition. The electrical and structural characteristics of BNdT thin films were investigated to develop ferroelectric thin films for capacitor layers of FRAM. After spin coating, thin films were annealed at $650^{\circ}C$ for 1hour in oxygen atmosphere. Scanning electron micrographs showed uniform surfaces composed of rod-like grains. The $Bi_{4-x}Nd_xTi_3O_{12}$(X=0.75) thin film capacitors with a Pt top electrode showed better ferroelectric properties. At the applied voltage of 5V, the dielectric constant$(\varepsilon_r)$, dissipation factor$(tan{\delta})$, remanent polarization(2Pr) and nonvolatile swiching charge of the $Bi_{4-x}Nd_xTi_3O_{12}$(x=0.75)thin films were about 346.7, 0.095, $56{\mu}C/cm^2$ and $38{\mu}C/cm^2$ respectively. Also the capacitor did not show any significant fatigue up to $8{\times}10^{10}$ read/write switching cycles at a frequency of 1MHz.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.757-763
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• 2019

A stacked high-voltage (900 V) Al electrolytic capacitor made with ZrO₂ coated anode foils, which has not been studied so far, is realized and the effects of Zr-Al-O composite layer on the electric properties are discussed. Etched Al foils coated with ZrO₂ sol are anodized in 2-methyl-1,3-propanediol (MPD)-boric acid electrolyte. The anodized Al foils are assembled with stacked structure to prepare the capacitor. The capacitance and dissipation factor of the capacitor with ZrO₂ coated anode foils increase by 41 % and decrease by 50 %, respectively, in comparison with those of Al anode foils. Zr-Al-O composite dielectric layer is formed between separate crystalline ZrO₂ with high dielectric constant and amorphous Al₂O₃ with high ionic resistivity. This work suggests that the formation of a composite layer by coating valve metal oxide on etched Al foil surface and anodizing it in MPD-boric acid electrolyte is a promising approach for high voltage and volume efficiency of capacitors.

• ETRI Journal
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• v.28 no.4
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• pp.475-485
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• 2006

Network-on-chip (NoC) is an emerging design paradigm intended to cope with future systems-on-chips (SoCs) containing numerous built-in cores. Since NoCs have some outstanding features regarding design complexity, timing, scalability, power dissipation and so on, widespread interest in this novel paradigm is likely to grow. The test strategy is a significant factor in the practicality and feasibility of NoC-based SoCs. Among the existing test issues for NoC-based SoCs, test access mechanism architecture and test scheduling particularly dominate the overall test performance. In this paper, we propose an efficient NoC-based SoC test scheduling algorithm based on a rectangle packing approach used for current SoC tests. In order to adopt the rectangle packing solution, we designed specific methods and configurations for testing NoC-based SoCs, such as test packet routing, test pattern generation, and absorption. Furthermore, we extended and improved the proposed algorithm using multiple test clocks. Experimental results using some ITC'02 benchmark circuits show that the proposed algorithm can reduce the overall test time by up to 55%, and 20% on average compared with previous works. In addition, the computation time of the algorithm is less than one second in most cases. Consequently, we expect the proposed scheduling algorithm to be a promising and competitive method for testing NoC-based SoCs.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.81-89
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• 2008

This paper is results of investigating the dominant factors influencing to coefficient of consolidation in horizontal direction of Korean marine clays and their correlations through literature review. From the results of analyzing data obtained from field tests such as piezocone penetration and dilatometer tests as well as laboratory tests, coefficient of consolidation in the horizontal direction was found to increase with increase of stiffness index of soil while it decreases with the increase of dissipation time of pore pressure developed during field tests. In general, the coefficient of consolidation in the horizontal direction tends to increase with increase of undrained shear strength and preconsolidation pressure although correlation between them are relatively low. Friction ratio has a high correlation with coefficient of consolidation in the horizontal direction in case of friction ratio being greater than 1.0. For methods of estimating coefficient of consolidation in the horizontal direction with different testing device, values obtained from methods of P2-logt and DMT-A with dilatometer were quite similar to values from piezocone penetration test. Consistency of soil is quite proportional to coefficient of consolidation in the horizontal direction. Clear correlation between coefficients of consolidation in the horizontal and the vertical directions could not be found. coefficient of consolidation in the horizontal direction estimated from the results of field test tends to be 1.13~3.11 times greater than that obtained from laboratory tests.

• Journal of the Korean Ceramic Society
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• v.31 no.2
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• pp.155-160
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• 1994

PZT ceramics substituted by La3+ and Nd3+ were fabricated according to the formula: [Pb1-x(La or Nd)x][Zr0.58Ti0.42]1-x/4$\square$x/4O3(x=0.00, 0.02, 0.05, 0.08, 0.15, 0.20). The crystal structure and microstructure were investigated by XRD and SEM. It was observed that the phase transitions among rhombohedral, tetragonal, and cubic symmetry occured as the substitutional quantity increased. Dielectric constant, dissipation factor and piezoelectric coefficient (d33), of each sample were measured. The dielectric properties were changed as the substitutional quanity of rare earth ion increased. These changes could be explained by crystal structure and compositional fluctuaction. Its d33 was higher at tetragonal region near to phase boundry between rhombohedral and tetragonal, which was explained by reorientation of domain wall.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.615-621
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• 2005

The electrical stability against surge stress of varistors, which are composed of Zn-Pr-Co-Cr-Y oxide system, were investigated at different sintering times. As sintering time increases, the varistor voltage and nonlinear exponent decreased in the range of $279.6\~179.1$ and $52.5\~24.9$, respectively. On the contrary, the leakage current and dielectric dissipation factor increased in the range of $1.2\~9.8\;{\mu}A$ and 0.0461\~0.0651 with increase of sintering time. For all varistors, the variation rates of V-I characteristic parameters against surge stress were more strongly affected in order of varistor voltage ${\rightarrow}nonlnear$ $exponent{\rightarrow}leakage$ current. On the whole, the electrical stability against surge stress increased with increasing sintering time. Conclusively, it is assumed that the varistors sintered for 2 h exhibited comparatively good characteristics, in view of overall characteristics.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.22-25
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• 2000

Polycrystalline SBTN layered ferroelectric thin film with various Nb mole ratios were prepared by sol-gel method Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperature and characterized in terms of phase and microstructure. The films were crystallized with a high (105) diffraction intensity and had rodike structure, SBTN films fired at 800$^{circ}C$ revealed standard hysteresis loops with no fatigue for up to 10$^{10}$ cycles. At an applied voltage of 5V the dielectric constant($varepsilon$) , dissipation factor (tan $delta$), remanent polarization(ZPr) and coercive field(Ec) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$) $O_{9+}$$alpha$/ thin film(x=0.1) prepared on Pt/ $SiO_2$/Si (100) were about 277.7, 0.042, 3.74$mu$C/$textrm{cm}^2$, and 24.8kv/cm respectively.ly.y. respectively.ly.y.y..

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.301-304
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• 2002

We investigated the structural and electrical properties of Ce-doped Ba($Zr_{0.2}Ti_{0.8}$)$O_3$(BCZT) thin films with a mole fraction of x=0.2 and a thickness about 100 nm. BCZT films were prepared on Pt/Ti/$SiO_2$/Si substrate by a RF magnetron sputtering system. We have measured the thickness profile with Ar/$O_2$ ratio and the surface roughness. It was observed that the oxygen gas, which introduced during the film deposition, have an influence on the roughness of the film and the film roughness was reduced by annealing from 2.33 nm to 2.02 m (RMS at $500^{\circ}C$, Ar:6 scrim, $O_2$:6 sccm). We have found that annealing procedure after top electrode deposit can reduce the dissipation factor.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1487-1489
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• 1998

In this paper, thin films of PI were fabricated VDPM of dry processes which are easy to control the film's thickness and hard to pollute due to volatile solvents. From FT-lR, PAA thin films fabricated by VDP were changed to PI thin films by thermal curing. From SEM, AFM and Ellipsometer experimental, as the higher curing temperatures the films thickness decreases and reflectance increases. Therefore, Pl could be fabricated stable by increasing curing temperature. The relative permitivity and dissipation loss factor were 3.7 and 0.008. Also, the resistivity was about $1.05{\times}10^{15}{\Omega}cm$ at $30^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.30 no.9
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• pp.695-700
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• 1993

In this study, we prepared Pb-Ti stock solution by sol-gel processing and deposited PbTiO3 thin film on a Pt coated SiO2/Si wafer by spin coating using the stock solution. We used lead acetate trihydrate and titanium isopropoxide. The stock solution was partially hydrolized and finally a 0.25M coating solution was prepared. We achieved spin coating at 4000rpm for 30 seconds and heated the thin film at 375$^{\circ}C$ for 5 minutes and at $600^{\circ}C$ for 5 minutes successively, first and second heating state. And the thin film was finally sintered at 90$0^{\circ}C$ for 1 hour in the air. The upper electrode of the thin film was made by gold sputtering and was cricle shape with radius 0.4mm. Measured dielectric constant, dissipation factor and phase transition temperature(Cuire Temp.) were about 275, 0.02 and 521$^{\circ}C$ respectively. To observe ferroelectric characteristics we calculated Pr(remnant polarization) and Ec(coercive field) byhysteresis curve. Ec was 72kV/cm and Pr was 11.46$\mu$C/$\textrm{cm}^2$.