• Journal of Ceramic Processing Research
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• v.20 no.4
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• pp.395-400
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• 2019

This study was conducted on the structural and electrical properties of (Ba0.7Sr0.3)TiO3 thin films prepared by the sol-gel and spin-coating methods in order to investigate their applicability to electrocaloric devices. All specimens showed a tetragonal crystal structure and lattice constants of a = 3.972 Å, c = 3.970 Å. The mean grain size of specimens sintered at 800 ℃ was about 30 nm, and the average thickness of 5 times coated specimens was 304~311 nm. In the specimen sintered at 750 ℃, The relative dielectric constant and loss of specimens measured at 20 ℃ were 230 and 0.130, respectively, while dependence of the dielectric constant on unit DC voltage was -8.163 %/V. The remanent polarization and coercive fields were 95.5 μC/㎠ and 161.3 kV/cm at 21 ℃, respectively. And, the highest electrocaloric property of 2.69 ℃ was observed when the electric field of 330 kV/cm was applied.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.2
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• pp.73-76
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• 2004

0-3 PbTiO$_3$/P(VDF/TrFE) nanocomposite thin films for passive pyroelectric infrared sensors were fabricated by a two-step spin coating technique. 65wt% VDF and 35 wt% TrFE was formed into a P(VDF/TrFE) powder. Nano size PbTiO$_3$ powder was used. 0-3 connectivity of PbTiO$_3$/P(VDF/TrFE) composite film was successfully achieved and observed using SEM photography. The dielectric constant and pyroelectric coefficient were measured and compared with P(VDF/TrFE). A very low dielectric constant (13.48 at 1KHz and sufficiently high pyroelectric coefficient (3.101 nC/$\textrm{cm}^2$ㆍk at 5$0^{\circ}C$) were measured. This nanocomposite can be used for a new pyroelectric infrared sensor to achieve better performance.

• Journal of the Korean Ceramic Society
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• v.21 no.1
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• pp.60-66
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• 1984

During the metallization in the manufacturing of the ceramic capacitor at the boundary layer between Pd or Pt electrode and $BaTiO_3$-dielectric reactions were analysed. For the study of the reaction Electron Spin Resonance (ESR) Method was used. With the aid of ESR an increased of the concentration of the paramagnetic $Ti^{3+}$-Centers on the metallizing process could be seen. It meaned a reduction effect although the metallization was accomplished under oxidation atmosphere. Therefore it could be regarded as a reaction at the boundary layer. In order to investigate the reaction ad double octahedral model was compared and the increase of the $Ti^{3+}$-concentration was studied.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.237-241
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• 1998

In this study, PLZT stock solutions around x/65/35 (x=6~11) ferroelectric region were prepared by Sol-Gel method and deposited on ITO-glass by spin-coating method. The thin films were annealed by RTA(rapid thermal annealing). The variations of crystallographic structure of the thin films were observed using XRD and hysteresis curves, dielectric characteristics, and optical transmittances were measured in order to investigate the characteristics of the thin films. The thin films were crystallized at $750^{\circ}C$ for 5 min by RTA. Relative dielectric constant and optical transmittance increased with increasing La content, Ec and Pr were higher for thin films than for bulk materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.311-314
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• 1999

Ferroelectric PZT heterolayered thin films were fabricated by spin coating method on the Pt/Ti/SiO$_2$/Si substrate using PZT(10/90) and PZT(90/10) metal alkoxide solutions. All PZT heterolayered films showed a homogeneous grain structure without presence of the rosette structure. It can be assumed that the lower PZT layers a role of nucleation site or seeding layer for the formation of the upper PZT layer. Zr and Ti diffusion into the Pt electrode were mainly distributed at the surface of Pt electrode beneath the PZT/Pt interface. The PZT/Pt interfacial layer showed a microstructure characterized by a grain phase surrounded by a Pb-deficient pyrochlore matrix phase. The relative dielectric constant and the dielectric loss of the PZT-6 film were 567 and 3.6, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.592-597
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• 2000

In this study (B $a_{0.5}$/S $r_{0.5}$)Ti $O_3$[BST(50/50)] ceramic thin films were prepared by the Sol-Gel method BST(50/50) stock solution was made and spin-coated on the Indium Tin Oxide(ITO)/glass substrate at 4000 rpm for 30 seconds. The coated films were dried at 35$0^{\circ}C$ for 10 minutes and annealed at 650~75$0^{\circ}C$ for 1 hour. The microstructural properties of the BST(50/50) thin film were studied by the XRD and AFM. The ferroelectric perovskite phase was formed at the annealing condition of 75$0^{\circ}C$ for 1 hour. Dielectric constant and loss of this thin were 370, 3.7% at room temperature respectively. The polarization switching voltage showed the good value of 3V. The leakage current density of the BST(50/50) thin film was 10$^{-7A}$c $m^2$with applied voltage of 1.5V. BST(50/50) thin film capacitors having good dielectric and electrical properties are expecting for the application to the dielectric material of DRAM.RAM.M.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.193-193
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• 2011

To obtain ceramic films, the sol-gel coating technique has been broadly used with heat treatment, but crack formation tend to occur during heat treatment in thick sol-gel films. We prepared PZT thin films by sol-gel method with single-step spin coating process. The PZT solution have been synthesized using lead acetate ($Pb(CH_3COO)_2$), zirconium acetylacetonate ($Zr(OC_3H_7^n)_4$), and titanium diisopropoxide bis(acetylacetonate) 75wt% in isopropanol ($Ti(OC_3H_7^i)_2(OC_3H_7^n)_2$) as starting materials and n-propanol was selected as a solvent. The poly(vynilpyrrolidone) (PVP) was added with 0, 0.25, 0.5, 0.75, and 1 molar ratios to control viscosity of solution. We investigated influence of the viscosity on thickness, microstructure, and electrical properties of final PZT films. Thermo-gravimetric analysis and differential scanning calorimeter (TGA/DSC) was carried out from room temperature to $800^{\circ}C$ in order to measure pyrolysis temperature. Structural characteristics were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ferroelectric and dielectric properties were measured by RT66A (Radiant) and impedance analyzer (Agilent), respectively. The thicknesses of PZT films depended on incorporation of an excess amount of PVP. Finally, we obtained PZT films of good quality without crack formation via single-step spin coating.

• Journal of Information Display
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• v.4 no.2
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• pp.1-6
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• 2003

In this paper, we demonstrate that the organic electrophosphorescent device is driven by the organic thin film transistor with spin-coated photoacryl gate insulator. It was found that electrical output characteristics in our organic thin film transistors using the staggered-inverted top-contact structure showed the non-saturated slope in the saturation region and the sub-threshold nonlinearity in the triode region, where we obtained the maximum power luminance that was about 90 $cd/m^2$. Field effect mobility, threshold voltage, and on-off current ratio in 0.45 ${\mu}m$ thick gate dielectric layer were 0.17 $cm^2/Vs$, -7 V, and $10^6$ , respectively. In order to form polyimide as a gate insulator, vapor deposition polymerization process was also introduced instead of spin-coating process, where polyimide film was co-deposited by high-vacuum thermal evaporation from 4,4'-oxydiphthalic anhydride (ODPA) and 4,4'-oxydianiline (ODA) and cured at 150${\sqsubset}$for 1hr. It was also found that field effect mobility, threshold voltage, on-off current ratio, and sub-threshold slope with 0.45 ${\mu}m$ thick gate dielectric films were 0.134 $cm^2/Vs$, -7 V, and $10^6$ A/A, and 1 V/decade, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.214.2-214.2
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• 2013

Device performance for the 45 and 32 nm node CMOS technology requires the integration of ultralow-k materials. To lower the dielectric constant for PECVD and spin-on materials, partial replacement of the solid network with air (k=1.01) appears to be more intuitive and direct option. This can be achieved introducting of second "labile" phase during depositoin that is removed during a subsequent UV curing and annealing step. Besides, with shrinking line dimensions the resistivity of barrier films cannot meet the International Technology Roadmap for Semiconductors (ITRS) requirements. To solve this issue self-forming diffusion barriers have drawn attention for great potential technique in meeting all ITRS requirments. In this present work, we report a Cu-V alloy as a materials for the self-forming barrier process. And we investigated diffusion barrier properties of self-formed layer on low-k dielectrics with or without UV curing treatment. Cu alloy films were directly deposited onto low-k dielectrics by co-sputtering, followed by annealing at various temperatures. X-ray diffraction revealed Cu (111), Cu (200) and Cu (220) peaks for both of Cu alloys. The self-formed layers were investigated by transmission electron microscopy. In order to compare barrier properties between V-based interlayer on low-k dielectric with UV curing and interlayer on low-k dielectric without UV curing, thermal stability was measured with various heat treatment temperature. X-ray photoelectron spectroscopy analysis showed that chemical compositions of self-formed layer. The compositions of the V based self-formed barriers after annealing were strongly dominated by the O concentration in the dielectric layers.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.607-613
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• 1989

The chemical equilibria of Ni(II)-tetraamine (tetraamine = 2,12-dimethyl-3,7,11,17-tetraazabicyclo-11,3,1-heptadeca-1(17),2,11,13,15-pentaene) complex ion in water, acetonitrile, acetone and nitromethane were investigated using spectrophotometric method, respectively. The equilibria between low-spin ($D_{4h}$) and high-spin ($O_h$) structures of Ni-tetraamine complex ion were presented in water, acetonitrile and acetone, but not in nitromethane. The eqilibrium constants, the reaction enthalpies and the reaction entropies were determined from analysis of the temperature dependence of the electronic spectra. The formation of the triplet species ($O_h$) was found to be exothermic. The solvent and electrolyte effects on the equilibrium constants could be explained by the dielectric constants of solvents and the reaction entropies.