• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.370-374
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• 2002

This paper describes the design and fabrication of distributed analog phase shifter circuit. The phase shifter consist of coplanar waveguide(CPW) lines that are periodically loaded with voltage tunable (Ba,Sr)TiO$_3$ thin film interdigital(IDT) capacitors deposited by the pulsed laser deposition(PLD) on (001) MgO single crystals. The phase velocity on these IDT loaded CPW lines is a function of applied bias voltage, thus resulting in analog phase shifting circuits. The measured differential phase shift is 48$^{\circ}$ and the insertion loss decreases from -5㏈ to -3㏈ with increasing bias voltage from 0 to 40 V at 100㎐.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.214-214
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• 2010

The 0.65Pb($Mg_{1/3}Nb_{2/3})O_3-0.35PbTiO_3$ (PMN-PT) thin films with $La_{0.5}Sr_{0.5}CoO_{3-\delta}$ (LSCO) bottom electrodes were grown on $CeO_2$/YSZ/Si(001), Pt/$TiO_2$/Si and $SrTiO_3$ (STO) substrates using conventional pulsed laser deposition (PLD) at a substrate temperature of $550^{\circ}C$. Since generally the crystallographic orientation of the bottom electrode induces the orientation of the films deposited on it, it allows us to observe the influence of the PMN-PT film orientation on the electrical properties. Phi scan done on PMN-PT/LSCO thin films shows epitaxial behavior of the films grown on sto substrates and $CeO_2$/YSZ buffered Si(001) substrates, and (110) texture on Pt/$TiO_2$/Si substrates. Polarization-electricfield (P-E) measurement shows good hysteresis behavior of PMN-PT films with remnant polarization of 18.2, 8.8, and $4.4{\mu}C/cm^2$ on $CeO_2$/YSZ/Si, Pt/TiO2/Si and STO substrates respectively.

• Korean Journal of Materials Research
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• v.19 no.10
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• pp.550-554
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• 2009

Unreported dielectrics based on the binary system of MgO-SiO$_2$ were investigated as potential candidates for microwave dielectric applications, particularly those demanding a high fired density and high quality factors. Extensive dielectric compositions having different molar ratios of MgO to SiO$_2$, such as 2:1, 3:1, 4:1, and 5:1, were prepared by conventional solid state reactions between MgO and SiO$_2$. 1 mol% of V$_2$O$_5$ was added to aid sintering for improved densification. The dielectric compositions were found to consist of two distinguishable phases of Mg$_2$SiO$_4$ and MgO beyond the 2:1 compositional ratio, which determined the final physical and dielectric properties of the corresponding composite samples. The increase of the ratio of MgO to SiO$_2$ tended to improve fired density and quality factor (Q) without increasing grain size. As a promising composition, the 5MgO.SiO$_2$ sample sintered at 1400 $^{\circ}C$ exhibited a low dielectric constant of 7.9 and a high Q $\times$ f (frequency) value of $\sim$99,600 at 13.7 GHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.61-64
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• 2003

This paper presents Bi thin films have been fabricated by atomic layer-by-layer deposition and co-deposition at an IBS method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. Mg(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and $820^{\circ}C$ and the highly condensed ozone gas pressure$(PO_3)$ in vacuum chamber was varied between $2.0{\times}10^{-6}$ and $2.3{\times}10^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and $795^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785^{\circ}C$. Whereas, $O_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.615-618
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• 2003

This paper presents Bi thin films have been fabricated by atomic layer-by-layer deposition and co-deposition at an IBS method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(l00) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 820 $^{\circ}C$ and the highly condensed ozone gas pressure(PO$_3$) in vacuum chamber was varied between 2.0$\times$10$^{-6}$ and 2.3$\times$10$^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795$^{\circ}C$ and single phase of Bi 2201 existed in the lower region than 785 $^{\circ}C$. Whereas, PO$_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with T$_{c}$(onset) of about 90 K and T$_{c}$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as CaCuO$_2$ was observed in all of the obtained films.lms.

• Proceedings of the Korean Vacuum Society Conference
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• 2003.08a
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• pp.214-214
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• 2003

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1480-1483
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• 2005

Transparent thin composite films (TCFs) were deposited on OLED devices by means of RF sputtering method and their passivation-properties were evaluated by comparing to the e-beam evaporating method. This composite film formed by mixed ratio of MgO (3wt %): $SiO_2$ (1wt %) was developed from pallet as a source of e-beam evaporator to 6-inch size target for sputtering in order to apply for large-sized organic display devices. Water Vapor Transmission Rates (WVTR) of the deposited films were measured as a function of thickness to assess the effectiveness of this film as a passivation layer and it applied to real devices. From this study, we can confirm that the passivation layer formed by TCFs using RF sputtering method sufficiently shows the potentiality of application to passivation layer for organic display devices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.235-243
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• 1997

The high-$T_c$ superconducting phase, $YBa_2Cu_3O_x$, was deposited on the single crystal MgO substrate, using a liquid aerosol feed method in a plasma enhanced chemical vapor deposition(PECVD) reactor. The effect of the plasma distribution depending on the design of a reactor was studied by the analysis of the microstructures of thin films. The particles landed were frequently observed on the films and the two causes that were responsible for the particle deposition were explained. The particles were deposited by the unstable and non-uniform plasma and the low evaporation rate of the precursors. Also, the thin film deposition rate decreased significantly as the distance between the evaporating location and the substrate increased.

• Korean Journal of Materials Research
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• v.7 no.5
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• pp.431-433
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• 1997

We investigated a double ring resonator(DRR)device to improve the resonating Q value of a superconductor resonator. To make a DRR device, we made a large area YBCO film on a MgO substrate by pulsed laser deposition(PLD). Thetransition temperature was 88 K and the film was uniformly deposited. We also deposited 500$\AA$SrTiO$_{3}$on the YBCO thin film to protect the superconducting properties from degradation. The loaded Q value was measured as 50000 from simulation and as 2000 from experiment near 10GHz at 77K.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.395-403
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• 2006

It is known that $MgAl_2O_4$ has higher resistance to moisture than MgO, in humid ambient MgO is chemically unstable. It reacts very easily with moisture in the air. In this study, the characteristic of $MgAl_2O_4$ and $MgAl_2O_4/MgO$ layers as dielectric protection layers for AC- PDP (Plasma Display Panel) have been investigated and analysed in comparison for conventional MgO layers. MgO and $MgAl_2O_4$ films both with a thickness of $1000\AA$ and $MgAl_2O_4/MgO$ film with a thickness of $200/800\AA$ were grown on the Cu substrates using the electron beam evaporation. $1000\AA$ thick aluminium layers were deposited on the protective layers in order to avoid the charging effect of $Ga^+$ ion beam while the focused ion beam(FIB) is being used. We obtained sputtering yieds for the MgO, $MgAl_2O_4$ and $MgAl_2O_4/MgO$ films using the FIB system. $MgAl_2O_4/MgO$ protective layers have been found th show $24{\sim}30%$ lower sputtering yield values from 0.244 up to 0.357 than MgO layers with the values from 0.364 up to 0.449 for irradiated $Ga^+$ ion beam with energies ranged from 10 kV to 14 kV. And $MgAl_2O_4$ layers have been found to show lowest sputtering yield values from 0.88 up to 0.109. Secondary electron emission coefficient(g) using the ${\gamma}$- FIB. $MgAl_2O_4/MgO$ and MgO have been found to have similar g values from 0.09 up to 0.12 for indicated $Ne^+$ ion with energies ranged from 50 V to 200 V. Observed images for the surfaces of MgO and $MgAl_2O_4/MgO$ protective layers, after discharge degradation process for 72 hours by SEM and AFM. It is found that $MgAl_2O_4/MgO$ protective layer has superior hardness and degradation resistance properties to MgO protective layer.