• Korean Chemical Engineering Research
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• 제55권4호
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• pp.556-560
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• 2017

A hemoglobin/silver nanoparticle heterolayer was fabricated for bioelectronic device with electrochemical signal-enhancement effect. As a device element, a hemoglobin, the metalloprotein, contained the heme group that showed the redox property was introduced for charge storage element. For electron transfer facilitation, a silver nanoparticle was introduced for electrochemical signal facilitation, the hemoglobin was immobilized onto Au substrate using chemical linker 6-mercaptohexanoic acid (6-MHA). Then, the silver nanoparticle was immobilized onto fabricated hemoglobin/6-MHA heterolayers by layer-by-layer (LbL) method. The surface morphology and surface roughness of fabricated heterolayer were investigated by atomic force microscopy (AFM). The redox property of hemoglobin/silver nanoparticle heterolayer was investigated by a cyclic voltammetry (CV) experiment for obtaining an oxidation potential and reduction potential. Moreover, for the assessing charge storage function, a chronoamperometry (CA) experiment was conducted to hemoglobin/silver nanoparticle-modified heterolayer electrode using oxidation and reduction potentials, respectively. Based on the results, the fabricated hemoglobin/silver nanoparticle heterolayer showed that an increased charge storage effect compared to hemoglobin monolayer-modified electrode.

• 한국전기전자재료학회논문지
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• 제37권3호
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• pp.297-303
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• 2024

In this study, KTN heterolayer thin films were fabricated by alternately stacking films of K(Ta_0.70Nb_0.30)O₃ and K(Ta_0.55Nb_0.45)O₃ synthesized using the sol-gel method. The sintering temperature and time were 750℃ and 1 hour, respectively. All specimens exhibited a polycrystalline pseudo-cubic crystal structure, with a lattice constant of approximately 0.398 nm. The average grain size was around 130~150 nm, indicating relatively uniform sizes regardless of the number of coatings. The average thickness of a single-coated film was approximately 70 nm. The phase transition temperature of the KTN heterolayer films was found to be approximately 8~12℃. Moreover, the 6-coated KTN heterolayer film displayed an excellent dielectric constant of about 11,000. As the number of coatings increased, and consequently the film thickness, the remanent polarization increased, while the coercive field decreased. The 6-coated KTN heterolayer film exhibited a remanent polarization and coercive field of 11.4 μC/cm² and 69.3 kV/cm at room temperature, respectively. ΔT showed the highest value at a temperature slightly above the Curie temperature, and for the 6-coated KTN heterolayer film, the ΔT and ΔT/ΔE were approximately 1.93 K and 0.128×10^-6 K·m/V around 40℃, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.153-156
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• 2004

The $Pb(Zr_{0.4}Ti_{0.6})O_3/Pb(Zr_{0.6}Ti_{0.4})O_3$ [PZT(4060)/(6040)] heterolayered thin films were deposited by RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrate. The effects of the structural and dielectric properties of PZT heterolayered thin films were investigated. The MFM(Metal Ferroelectric Metal) type capacitors were made using the PZT(6040)/(4060) heterolayered thin films deposited with optimum deposition condition. An enhanced dielectric property was observed in the PZT(4060)/(6040) thin films. Investigating the dielectric constant and dielectric loss characteristics. the application for the next-generation dielectric thin films and memory devices were studied.

• 전기학회논문지
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• 제58권12호
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• pp.2431-2435
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• 2009

The heterolayered BT/BNT thick films were fabricated by screen printing techniques on alumina substrates electrodes with Pt. We report the improved ferroelectric and dielectric properties in the heterolayered tetragonal/rhombohedral structure composed of the BT and the BNT thick films. We investigated the effects of deposition conditions on the structural and electrical properties of the heterolayered BT/BNT thick films. The dielectric properties of the heterolayered BT/BNT thick films were superior to those of single composition BNT, and those values for the heterolayered BT/BNT thick films were 1455, 0.025 and $12.63 {\mu}C/cm^2$.

• 한국세라믹학회지
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• 제49권5호
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• pp.404-411
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• 2012

The reliability of solid oxide fuel cells (SOFCs) particularly depends on the high quality of solid oxide electrolytes. The application of thinner electrolytes and multi electrolyte layers requires a more reliable characterization method. Most of the investigations on thin film solid electrolytes have been made for the parallel transport along the interface, which is not however directly related to the fuel cell performance of those electrolytes. In this work an array of ion-blocking metallic Ti/Au microelectrodes with about a $160{\mu}m$ diameter was applied on top of an ultrathin ($1{\mu}m$) yttria-stabilized-zirconia/gadolinium-doped-ceria (YSZ/GDC) heterolayer solid electrolyte in a micro-SOFC prepared by PLD as well as an 8-${\mu}m$ thick YSZ layer by screen printing, to study the transport characteristics in the perpendicular direction relevant for fuel cell operation. While the capacitance variation in the electrode area supported the working principle of the measurement technique, other local variations could be related to the quality of the electrolyte layers and deposited electrode points. While the small electrode size and low temperature measurements increaseed the electrolyte resistances enough for the reliable estimation, the impedance spectra appeared to consist of only a large electrode polarization. Modulus representation distinguished two high frequency responses with resistance magnitude differing by orders of magnitude, which can be ascribed to the gadolinium-doped ceria buffer electrolyte layer with a 200 nm thickness and yttria-stabilized zirconia layer of about $1{\mu}m$. The major impedance response was attributed to the resistance due to electron hole conduction in GDC due to the ion-blocking top electrodes with activation energy of 0.7 eV. The respective conductivity values were obtained by model analysis using empirical Havriliak-Negami elements and by temperature adjustments with respect to the conductivity of the YSZ layers.

• Transactions on Electrical and Electronic Materials
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• 제6권5호
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• pp.210-213
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• 2005

The $BaTiO_3/SrTiO_3$ heterolayered thick films were fabricated by the screen printing method on alumina substrates. The effect of the sintering temperature on the microstructure and dielectric properties of the $BaTiO_3/SrTiO_3$ thick films has been investigated. The relative dielectric constant and dielectric loss at 1 MHz of the $BaTiO_3/SrTiO_3$ heterolayered thick films with sintering temperature of $1350^{\circ}C$ were about 751 and 1.74, respectively. The remanent polarization $(P_r)$ of the pure $(Ba_{0.5}Sr_{0.5})TiO_3$ and $BaTiO_3/SrTiO_3$ heterolayered films are approximately $5.1\;{\mu}C/cm^2$ and $10\;{\mu}C/cm^2$. This study suggests that the design of the $BaTiO_3/SrTiO_3$ heterolayered thick films capacitor with different phase should be an effective method to enhance the dielectric and ferroelectric performance in devices.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.194-196
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• 2004

$BaTiO_3/SrTiO_3$ heterolayered thick films on the $Al_2O_3$ substrate by screen printing method with stacking periodicity. The stacking periodicity of $BaTiO_3/SrTiO_3$ heterolayer structure was varied from $(BaTi_O_3)_1/(SrTiO_3)_1$ to $(BaTi_O_3)_3/(SrTiO_3)_3$. The total thickness of the $BaTiO_3/SrTiO_3$ films was about $120{\mu}m$. There was an interdiffusion at the interface of the $BaTiO_3$ and $SrTiO_3$ layers. The dielectric constant of $BaTiO_3/SrTiO_3$ heterolayered thick films was increased with decreasing stacking periodicity of the $BaTiO_3/SrTiO_3$. The dielectric constant of the ($(BaTi_O_3)_1/(SrTiO_3)_1$ herterolayered thick films was about 1780.