• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.615-616
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• 2005

Carbon Nanotubes (CNT) on flexible indium tin oxide (ITO) PET films were prepared for dye-sensitized solar cell (DSSC). These CNTs were prepared by spray coating method for various amount of light transparency. Also, Pt counter electrode was prepared by electro deposition method. All $TiO_2$ electrodes were deposited on ITO-PET films by spray coating method. Micro structural images show that CNT counter electrodes prepared by spray-coating have more dense structure with increasing spraying time (0 to 60 seconds). DSSC consisting of $TiO_2$ electrode and CNT counter electrode was fabricated with various amount of light absorption. DSSC have higher light energy conversion efficiency with increasing the thickness of CNT counter electrode. CNT counter electrode is at least compatible to that of CNT counter electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.135-136
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• 2006

Bismuth titanate ($Bi_4Ti_3O_{12}$, BIT) thin film has been studied intensively in the past decade due to its large remanent polarization, low crystallization temperature, and high Curie temperature. Substitution of various trivalent rare-earth cations (such as $La^{3+}$, $Nd^{3+}$, $Sm^{3+}$ and $Pr^{3+}$) in the BIT structure is known to improve its ferroelectric properties, such as remanent polarization and fatigue characteristics. Among them, neodymuim-substituted bismuth titanate, ((Bi, Nd)$_4Ti_3O_{12}$, BNT) has been receiving much attention due to its larger ferroelectricity. In this study, Ferroelectric $Bi_{3.3}Nd_{0.7}Ti_3O_{12}$ thin films were successfully fabricated by liquid delivery MOCVD process onto Pt(111)/Ti/$SiO_2$/Si(l00) substrates. Fabricated polycrystailine BNT thin films were found to be random orientations, which were confirmed by X-ray diffraction and scanning electron microscope analyses. The remanent polarization of these films increased with increase in annealing temperature. And the film also demonstrated fatigue-free behavior up to $10^{11}$ read/write switching cycles. These results indicate that the randomly oriented BNT thin film is a promising candidate among ferroelectric materials useful for lead-free nonvolatile ferroelectric random access memory applications.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.960-964
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• 2001

$Bi_{3.99}Ti_{2.97}V_{0.03}O_{12}$ (BTV) thin films with 3 mol% vanadium doping were Prepared on $Pt/Ti/SiO_2/Si$ substrate by sol-gel method. X-ray diffraction analysis indicated that single-phase layered perovskite were obtained and preferred orientation was not observed. Under the annealing temperature at $600^{\circ}C$, the surface morphology of the BTV thin films had fine-rounded particles and then changed plate-like at $650^{\circ}C$ and $700^{\circ}C$. The remanent polarization $(2P_r)$ and coercive field $(2E_c)$ of $700^{\circ}C$ annealed BTV thin film were 25 $\mu$C/cm$^2$ and 116 kV/cm, respectively. In addition, BTV thin film showed little polarization fatigue during $10_9$ switching cycles. These improved ferroelectric properties were attributed to the increased rattling space and reduced oxygen vacancies by substitution $Ti^{4+}$ ion (68 pm) with smaller $V^{5+}$ ion (59 pm). The dielectric constant and loss were measured 130 and 0.03 at 10 kHz, respectively.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.166-171
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• 2006

In this study, in using a piezoelectric material of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ (PMN-PT), which has a high electromechanical coupling coefficient, we have tried to study about this material can be practically available as a new biosensor to detect protein by using surface acoustic wave (SAW). As the results, the filtering of the center frequency of the PMN-PT substrate is a superior result to that of the $LiTaO_3$ (LT) substrate, but the result was not completely satisfactory. Also this study attempts to develop a sensing method to detect mismatched DNA in order to diagnose cancer. We could directly immobilize the MutS to the NTA using the EDC solution. But, we immobilized MutS using nickel and it is judged that is more effective method to detect mismatched DNA.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.4
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• pp.232-238
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• 2000

PZT thin films(3500 ) have been prepared onto $Pt/Ti/SiO_2/Si$ substrates with a RF magnetron sputtering system using PB1.05(Zr0.52,Ti0.48)O3 ceramic target. We used two-step annealing techniques. As the RTA times and temperatures were increased, crystallization of PZT thin films were enhanced. The ferroelectric characteristics of PZT capacitors fabricated at $700^{\circ}C$ for 60 seconds were like these remanent polarization were $12.1 \muC/cm^2$, coercive field were 110 kV/cm, leakage current density were $4.1\times10-7 A/cm^2,\; \varepsilonr=442,$ and remanent polarization were decreased by 22% after 1010 cycles, respectively.

• Journal of the Korean Vacuum Society
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• v.4 no.S1
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• pp.145-150
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• 1995

PZT thin films were fabricated on Pt/Ti/SiO2/Si substrates at $500^{\circ}C$ by ECR-PECVD for the application to the charge storage capacitor of ULSI DRAMs. Perovskite single phase PZT films were obtained by controling the film compositional ratio Pb/(Zr+Ti) close to 1. The anion concentrations in the PZT films were successfully controlled by adjusting the flow rates of each MO sources. Capacitance of a typical 94 nm thick PZT film prepared at $500^{\circ}C$ in this work was about 5.3 uF/$\textrm{cm}^2$, which corresponds to the equivalent SiO2 thickness of 0.65nm.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.1046-1049
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• 1998

PLT(28) ($Pb_{0.72}La_{0.28}Ti_{0.93}O_3$) dielectric thin films have been deposited on Pt/Ti/$SiO_2$/Si substrates in situ by a laser ablation. We have systematically changed the laser fluence from $0.5\;J/cm^2$ to $3\;J/cm^2$, and deposition temperature from $450^{\circ}C$ to $700^{\circ}C$. The surface morphology was changed from planar grain structure to columnar structure as the nucleation energy was increased. The PLT thin film with columnar structure showed good dielectric properties. It is shown that the deposition temperature strongly affect the film nucleation compared with the laser fluence.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.225-227
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• 1993

Pb(Zr, Ti)$O_3$ ferroelectric thin layers were deposited onto Pt/$SiO_2$/Si substrates by Sol-Gel processing and annealed by RTA at $600^{\circ}C$ for $20{\sim}30\;sec$. microstructure of the films was examined by XRD and SEM analysis. Electrical properties of PZT thin films with different Zr/Ti ratio yield $P_r$ ranging $10{\sim}21{\mu}C/cm^2$, $E_c$, ranging $37.5{\sim}137.5\;kV/cm$, switching times faster than 180nsec, and leakage current about $20{\mu}A/cm^2$. The film was endured about $10^{10}$ fatigue cycles.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.550-553
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• 2005

[ $Pb(Zr_{0.2}Ti_{0.8})O_3$ ] powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT thick films were fabricated by the screen-printing techniques on Pt/alumina substrates. The structural and dielectric properties were examined as a function of sintering temperature. The particle size distribution of the powder is bimodal with the mean particle size of about $1.2\;{\mu}m$. The average grain size of the PZT thick films sintered above $1000^{\circ}C$ was about $3.1\;{\mu}m$ and the thickness of the specimens was approximately $41\;{\mu}m$. The relative dielectric constant and dielectric loss of the thick films sintered at $1050^{\circ}C$ were 337 and $1.24\%$, respectively.