• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.185-190
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• 2003

In this paper, it was demonstrated that the organic thin film transistors were fabricated by the organic gate insulators with vapor deposition polymerization (VDP) processing. 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 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and ODA, and cured at $150^{\circ}C$ for 1hr. Electrical output characteristics in our organic thin film transistors using the staggered-inverted top-contact structure obtained to the saturated slop in the saturation region and the subthreshold non-linearity in the triode region. Field effect mobility, threshold voltage, and on-off current ratio in $0.45\;{\mu}m$ thick gate dielectric layer were about $0.17\;cm^2/Vs$, -7 V, and $10^6\;A/A$, respectively. Details on the explanation of compared to organic thin-film transistors (OTFTS) electrical characteristics of ODPA-ODA and 6FDA-ODA as gate insulators by fabricated thermal co-deposition method.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.446-448
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• 2000

Organic semiconductors based on vacuum-deposited films of fused-ring polycyclic aromatic hydrocarbon have great potential to be utilized as an active layer for electronic and optoelectronic devices. In this study, pentacene thin films and electrode materials were deposited by Organic Molecular Beam Deposition (OMBD) and vacuum evaporation respectively. For the gate dielectric layer, OPTMER PC403 photo acryl (JSR Coporation.) was spin-coated and cured at $220^{\circ}C$. Electrical characteristics of the devices were investigated, where the channel length and width was $50{\mu}m$ and 5 mm. It was found that field effect mobility was $0.039\;cm^2V^{-1}s^{-1}$, threshold voltage was -7 V, and on/off current ratio was $10^6$.

• Journal of Magnetics
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• v.8 no.1
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• pp.24-31
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• 2003

The discoveries of antiferromagnetic coupling in Fe/Cr multilayers by Grunberg, the Giant Magneto Resistance by Fert and Grunberg and a large tunneling magnetoresistance at room temperature by Moodera have triggered enormous research on magnetic thin films and magnetoelectronic devices. Large opportunities are especially opened by the spin dependent tunneling resistance, where a strong dependence of the tunneling current on an external magnetic field can be found. We will briefly address important basic properties of these junctions like thermal, magnetic and dielectric stability and discuss scaling issues down to junction sizes below 0.01 $\mu\textrm{m}$$^2$with respect to single domain behavior, switching properties and edge coupling effects. The second part will give an overview on applications beyond the use of the tunneling elements as storage cells in MRAMs. This concerns mainly field programmable logic circuits, where we demonstrate the clocked operation of a programmed AND gate. The second 'unconventional' feature is the use as sensing elements in DNA or protein biochips, where molecules marked magnetically with commercial beads can be detected via the dipole stray field in a highly sensitive and relatively simple way.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.123-124
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• 2006

The sandwiched PZT/$BaTiO_3$/PZT thick films were fabricated by two different methods thick films of the PZT by screen printing method on alumina substrateselectrodes with Pt, thin films of $BaTiO_3$ by the spin-coating method on the PZT thick films and once more thick films of the PZT by the screen printing method on the $BaTiO_3$ layer. The structural and the dielectric properties were investigated for effect of various stacking sequence of sol-gel prepared $BaTiO_3$ coating solution at interface of the PZT thick films, The insertion of BaTi03 interlayer yielded the PZT thick films with homogeneous and dense grain structure with the number of $BaTiO_3$ layers. The leakage current density of the $PZT/BaTiO_3-1$ film is less that $4.41{\times}10^{-9}A/cm^2$ at 5 V.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.202-208
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• 2010

This study examined the dependency of crystalline orientation and electric properties of sol-gel PZT film on hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The PZT thin films were prepared by using 2-Methoxyethanol-based sol-gel method and spin-coating on Pt/Ti/$SiO_2$/Si substrates. The 1-${\mu}m$-thick PZT films were coated and then fired in a furnace by direct insert method. The highly (111) oriented PZT film of pure perovskite structure could be obtained. We could control the degree of orientation by various parameters such as hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The highest measured remanent polarization, dielectric constant and piezoelectric coefficient are $24.16\;{\mu}C/cm^2$, 2808, and 159 pC/N, respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.139-145
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• 2015

In this paper, the flexible piezoelectric nanocomposite generator(NCG) device based on $BaTiO_3$ nanostructures was fabricated via simple and low-cost spin coating method. The $BaTiO_3$ nanostructures synthesized by self-assembly reaction showed dendrite morphologies. To produce the piezoelectric nanocomposite(p-NC layer) which acts as an electric energy source in NCG device, the piezoelectric nanopowders($BaTiO_3$) were dispersed in polydimethylsiloxane(PDMS). Sequently, the p-NC layer was inserted in two dielectric layer of PDMS; these layers enabled the NCG device flexibility as well as durability prohibiting detachment(exfoliation) for significantly mechanical bending motions. The fabricated NCG device shows average maximum open circuit voltage of 6.2 V and average maximum current signals of 300 nA at 20 wt% composition of $BaTiO_3$ nanostructures in p-NC layer. Finally, the flexible energy harvester generates stable output signals at any rate of frequency which were used to operate LCD device without any external energy supply.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.339-342
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• 1998

Ferroelectric L $a_2$ $Ti_2$ $O_{7}$(LTO) thin films were prepared by chemical solution deposition processes. Acetylacetone was used as chelating agent and nitric acid was added in the stock solution to control hydrolysis and condensation reaction rate. The LTO thin films were spin-coated on Pt/Ti/ $SiO_2$/(100)Si and Pt/Zr $O_2$/ $SiO_2$/(100)Si substrates. After multiple coating, dried thin films were heat-treated for decomposition of residual organics and crystallization. The role of acetylacetone in Ti iso-propoxide stabilization by possibly substituting $O^{i}$Pr ligand was studied by H-NMR. B site-rich impurity phase, i.e. L $a_4$ $Ti_{9}$ $O_{24}$, was found after annealing, where its appearance was dependent on process temperature indicating the possible reaction with substrate. Dielectric and other relevant electrical properties were measured and the results were compared between modified sol-gel and MOD processes.s.s.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1758-1760
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• 1998

MgO Protecting layer in AC PDP prevents ion bombardment in discharge plasma. The MgO layer also has the additional importance in lowering the firing voltage due to a large secondary electron emission coefficient. Until now, the MgO protecting layer is mainly prepared by E-beam Evaporation. However, the optimum activation manufacturing process of MgO thin film wasn't well known. Therefore in this study, after MgO protecting layer is prepared on dielectric layer by E-beam evaporation and liquid MgO spin coating, we carried out activation process of MgO thin film as a parameter of Temperature, Operating time and Operating pressure. In addition, discharge characteristics are also studied as a parameter of activation conditions.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1488-1490
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• 1997

$(Pb_{1-x}La_x)Ti_{1-x/4}O_3$ (x=0, 0.02, 0.04, 0.06, 0.08) ceramic thin films were fabricated by Sol-Gel method. A stock solution of (Pb,La)$TiO_3$ with excess Pb 10mol% was made and spin-coated on the Pt/Ti/$SiO_2$/Si substrate at 4000rpm for 30 seconds. Coated specimens were dried on the hot-plate at $350^{\circ}C$ for 10 min and sintered at $500{\sim}750^{\circ}C$ for 1 hour. The dielectric constant, remanent polarization and coercive field of the PLT(6 at.%) thin films sintered at $650^{\circ}C$ were 884, $13.95{\mu}C/cm^2$ and 8.7kV/cm, respectively. Pyroelectric coefficient, figure of merit of pyroelectric current, voltage responsivity and detectivity of PLT(6at.%) thin films were $3.2{\times}10^{-8}\;C/cm^2K$, $1.02{\times}10^{-8}\;C{\cdot}cm/J$, $2.9{\times}10^{-11}\;C{\cdot}cm/J$, $0.29{\times}10^{-8}\;C{\cdot}cm/J$, respectively.

• Electrical & Electronic Materials
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• v.10 no.6
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• pp.541-547
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• 1997

(Pb$_{1-x}$ La$_{x}$)Ti$_{1-x}$ $_4$O$_3$(x=0, 0.02, 0.04, 0.08) ceramic thin films were fabricated by Sol-Gel method. A stock solution of (Pb, La)TiO$_3$ with excess Pb 10 mol% was made and spin-coated on the Pt/Ti/SiO$_2$/Si substrate at 400rpm for 30 seconds. Coated specimens were dried on the hot-plate at 35$0^{\circ}C$ for 10 min and sintered at 500~75$0^{\circ}C$ for 1 hour. The dielectric constant, remanent polarization and coercive field of the PLT(6at.%) thin films sintered at $650^{\circ}C$ were 884, 13.95$\mu$C/$\textrm{cm}^2$ and 8.7kV/cm, respectively. Pyroelectric coefficient, figure of merit of pyroelectric current, voltage responsivity and detectivity of PLT(6at.%) thin films were 3.2$\times$10$^{-8}$ C/$\textrm{cm}^2$K, 1.02$\times$10$^{-8}$ C.cm/J, 2.9 $\times$10$^{-11}$ C.cm/J, 0.29$\times$10$^{-8}$ C.cm/J, respectively.ely.