• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.10
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• pp.559-563
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• 2000

The $(Sr_{1-x}Ca_x)TiO_3(SCT)$ thin films are deposited on Pt-coated(Pt/TiN/$SiO_2$/Si) using RF sputtering method with substitutional contents of Ca. The maximum grain of thin films is obtained by substitution of Ca at 15[mol%]. Also the composition of SCT thin films were closed to stoichiometry(1.081∼1.117 in A/B/ ratio). The dielectric constant was increased with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mol%]. The dielectric constant changes almost linearly in temperature ranges of -80∼+90[^${\circ}C$]. The temperature properties of the dielectric loss have a stable value within 0.02 independent of the substitutional contents of Ca. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 2000[kHz]. The current-voltage characteristics of SCT15 thin films showed the increasing leakage current as the measuring temperature increase.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1115-1118
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• 2006

Using a thermally-crosslinkable organosiloxane-based organic-inorganic hybrid material, solution processable gate dielectric layer for organic thin-film transistors (OTFTs) have been fabricated. The hybrid dielectrics are synthesized by the sol-gel process, followed by the heat-treatment at $190{\bullet}\;.{\bullet}$ To investigate the electrical property of hybrid dielectric, leakage current behavior and capacitance were measured. To fabricate coplanar-type OTFTs, Au/Cr electrode was deposited onto the heavily doped silicon substrate with the organic-inorganic hybrid dielectric layer and then ${\alpha},{\omega}-dihexylquaterthiophene$ was drop-cast between source and drain electrical performance of the fabricated transistor.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.380-382
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• 1989

Dielectric breakdown strength (Eb) of thin Poly(Vinylidene Fluoride ; PVDF) film is studied in the temperature range between 4.2 K and 400 K. The results of this study can be summerized as follows. 1) Temperature dependence of dielectric breakdown strength (Eb) can be devided into high and low temperature regions. The critical temperature (Tc) at which two regions are devided depends on applied voltage. 2) Dielectric breakdown strength (Eb) by pulse voltage is higher than that by DC voltage. Especially this difference is remarkable at low temperature.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1051-1054
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• 2009

This paper investigates approaches for improving effective mobility of organic thin film transistors (OTFTs). We consider gate dielectric optimization, whereby we demonstrated >2x increase in mobility by using a silicon-rich silicon nitride ($SiN_x$) gate dielectric for polythiophene-based (PQT) OTFTs. We also engineer the dielectric-semiconductor ($SiN_x$-PQT) interface to attain a 27x increase in mobility (up to 0.22 $cm^2$/V-s) using an optimized combination of oxygen plasma and OTS SAM treatments. Augmentative material systems by combining 1-D nanomaterials (e.g., carbon nanotubes, zinc oxide nanowires) in an organic matrix for nanocomposite OTFTs provided a further boost in device performance.

• Electrical & Electronic Materials
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• v.10 no.1
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• pp.61-67
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• 1997

We have studied dielectric properties of sol-gel derived tantalum oxide thin films as the insulators. As the sample is annealed from 300.deg. C to 700.deg. C, it is found amorphous below 600.deg. C and crystalline over it. Dielectric constant is maximum(18.6) when Ta$_{2}$O$_{5}$ film was annealed at 400.deg. C. It is found that dielectric strength in Ta$_{2}$O$_{5}$ film annealed at 400.deg. C (1.5MV/cm) increases and then decreases over annealed at 500.deg. C. This phenomenon was attributed to pinhole effect and crystallization. The de conduction properties can be interpreted by Poole-Frenkel effect.ect.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.9-12
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• 2004

The effect of x wt% CuO-y wt% $V_2O_5$ content on the microwave properties of $(Pb_{0.45}Ca_{0.55})[(Fe_{0.5}Nb_{0.5})_{0.9}Sn_{0.1}]O_3$ (PCFNS) ceramics was investigated. In order to decrease the sintering temperature and use as a Low Temperature co-firing Ceramics (LTCC), CuO-$V_2O_5$ are added in the PCFNS. The bulk density, dielectric constant (${\varepsilon}_r$) and quality factor(Q${\cdot}f_0$) increased with increase in CuO content within a limited value. The microwave properties were degraded with increases in $V_2O_5$ content. The temperature coefficient of the resonant frequency (${\tau}_f$) of PCFNS was shifted to positive value abruptly with increasing the $V_2O_5$ content, while the ${\tau}_f$ was slightly shifted to positive value with increasing the CuO content. The optimized microwave properties, ${\varepsilon}_r$ = 88, Q${\cdot}f_0$ = 6100 (GHz), and ${\tau}_f$ = 18 ppm/$^{\circ}C$, were obtained in $(Pb_{0.45}Ca_{0.55})[(Fe_{0.5}Nb_{0.5})_{0.9}Sn_{0.1}]O_3$ with 0.2wt% CuO 0.05 wt% $V_2O_5$ and sintered at $1000^{\circ}C$ for 3 h. The relationship between the microstructure and microwave dielectric properties of ceramics was studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.288-291
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• 2002

An alkoxide-based sol-gel method was used to fabricate $(Pb_{x},Sr_{1-x})$TiO3 (PST) thin films on a Pt/Ti/SiO2/Si substrate, and the dielectric properties of the PST thin films were investigated as a function of the Pb/Sr composition for use in tunable microwave device applications. The dielectric properties of the PST films were strongly dependent on the Pb/Sr ratio. The dielectric constant and dielectric loss of the PST films increased with increasing Pb content, and the figure of merit (FOM) reached a maximum value of 27.5 at a Pb/Sr ratio of 4:6. The tunability increased with increasing Pb content. The dielectric constant, loss factor, and tunability of PST (50/50) thin films were 404, 0.023, and 51.73%, respectively. From the result, the PST films with good dielectric properties are useful candidates for tunable microwave device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.582-585
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• 2004

Pb0.5Sr0.5TiO3 (PST) thin films were fabricated by the alkoxide-based sol-gel process using spin-coating method on Pt/Ti/SiO2/Si substrate. The PST films annealed from 500C to 650C for 1h show a perovskite phase and dense microstructure with a smooth surface. The grain size and dielectric constant of PST films increases with the increase in annealing temperature, which reduces the SiO2 equivalent thickness of the PST film. The crystallinity or internal strain in the PST thin films analyzed from the diffraction-peak widths correlate well with the decrease in the dielectric losses. The dielectric constants and dielectric loss (%) of the PST films annealed at 650c (teq : 0.89 nm) were 549 and 0.21%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.56-59
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• 2000

In this study, Ferroelectric $Pb(Zr_x,Ti_{1-x})O_3$(x=0.53) thin films were fabricated by the spin-coating on the Pt/Ti/$SiO_2$/Si substrate using the PZT metal alkoxide solutions with various excess Pb contents. Etching of PZT film was performed using planar inductively coupled Ar(20)$/Cl_2/BCl_3$ plasma. The etch rate of PZT film was 2450 ${\AA}/min$ at Ar(20)$/BCl_3$(80) gas mixing ratio and substrate temperature of $80^{\circ}C$. The leakage current densities of before etching and after etching PZT thin film were $6.25\times10^{-8}A/cm^2$, $8.74\times10^{-7}A/cm^2$ with electric field of 0.07MV/em, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.142-142
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• 2003

The effects of film thickness on the dipolar relaxation of ferroelectric PbTiO$_3$ films were investigated in the microwave-frequency range. The dielectric constants ($\varepsilon$) and the dielectric losses (tan $\delta$) were successfully measured up to 30 ㎓ using interdigital capacitors. The PbTiO$_3$ thin films were deposited on the quartz substrate at room temperature and postannealed in oxygen atmosphere. As the film thickness increased, its grain size and tetragonality were enhanced. And the dipolar relaxation behavior began to appear in the thin films with approximately 20 nm thickness, since ferroelectric domains could not be formed hi small grains. The observed relaxation frequency (above 10 ㎓) was higher than the previous values reported in bulk ceramics. It can be correlated with the extremely small domain size of the thinfilms as shown by TEM. And, the Rayleigh constant [1] from domain wall motions was alsoinvestigated by LCR meter at 100 KHz.