• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.290-294
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• 2001

In this study, ZnO is evaporated to be coated on n-type Si wafer substrate. Refractive coefficient of thin film that is evaporating TiO$_2$ onto ZnO increases linearly as thickness is getting thinner to have high value and high angle and it satisfies theoretical equation I(x)=Io exp (-$\alpha$x) theory that represents the strength of photon energy advancing through ZnO thin film. And dielectric constant of TiO$_2$ thin film evaporated onto ZnO is high and $\varepsilon$$_2$ is smaller than $\varepsilon$$_1$. The specimen TiO$_2$ thin film evaporated onto ZnO has much higher dielectric constant when photon energy is increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.380-380
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• 2011

ZnO 나노라드 위에 양자점을 증착한 후 그 위에 $TiO_2$를 ALD방법으로 증착하여 그 passivation 효과가 solar cell 효율에 미친 영향에 대한 실험을 진행하였다. Hydrothermal 방법으로 수직한 1차원 형태의 ZnO 나노라드를 성장시킨다. 여기에 SILAR 방법을 거쳐서 CdS 양자점을 증착시키고, 후에 CBD를 이용하여 CdSe 양자점을 증착시킨다. 여기에 마지막으로 amorphous $TiO_2$로 표면을 덮는 과정을 거치는데, $TiO_2$가 ZnO 라드 위에 균일하고 정밀하게 증착되도록 하기 위해서 Atomic Layer Deposition을 이용하였다. 다양한 분석 방법을 통해 $TiO_2$/CdSe/CdS/ZnO 구조를 조사하였으며, ZnO 나노라드 위에 $TiO_2$가 정교하게 올라간 것을 확인한 후에 solar cell에 적용하여 그 효율을 확인하였다.

• Journal of Hydrogen and New Energy
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• v.28 no.4
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• pp.419-425
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• 2017

In this study, an efficient dye-sensitive solar cells (DSSC) was developed after post-treatment of ZnO on $TiO_2$ photoelectrode. The $TiO_2$ electrode with ZnO post treatment was prepared with Titanium isoporopoxide in Zinc Nitrate Hexahydrate aqueous solution by incineration for 30 min at $450^{\circ}C$. The ZnO-post treated $TiO_2$ electrode showed strong dispersion force between particles in relation to the control $TiO_2$, referring high specific surface area and dye-adsorption rate. Proper addition of ZnO enhanced electron mobility and reduced internal resistance and electron recombination. Light conversion efficiency of DSSCs containing the ZnO-posttreated $TiO_2$ electrode increased 35.4% when compared to the DSSCs using $TiO_2$ electrode. It is similar to the DSSCs with $TiCl_4$ post treatment $TiO_2$ electrode. Increasing of light conversion efficiency was due to high specific surface area and dispersion force, and low dye-adsorption rate and electron recombination. Taken together, ZnO may be used as posttreatment of photoelectrode and replaced $TiCl_4$ that has high toxicity and causticity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.121-124
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• 1998

Generally the structure of powder electroluminescent devices (PELDs) on ITO-film was makeup of the ZnS:Cu phosphor layer and BaTiO$_3$ insulating layer. The active layer, which consists of a suitably doped ZnS powder mixed in a dielectric, is sandwiched between two electrodes; one of which are ITO film and the other is aluminum. In this paper, three kinds of powder eleotroluminescent devices (PELDs) : WK-A(ITO/BaTiO$_3$/ZnS:Cu/Silver paste). WK-B(ITO/BaTiO$_3$+ZnS:Cu/Silver paste) and WK-C(ITO/BaTiO$_3$/ZnS:Cu/BaTiO$_3$/Silver paste), fabricated by spin coating method, were investigated. To evaluate the luminescence properties of three kinds of PELDs, EL emission spectroscopy, transferred charge density and time response of EL emission intensity under square wave voltage driving were measured.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.8
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• pp.1068-1074
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• 1995

Effect of (Zn$_{1}$3/Nb$_{2}$3/) $O_{2}$ addition on the phase changes and microwave dielectric properties of BaTi $O_{3}$-3Ti $O_{2}$ ceramics were investigated. Addition of (Zn$_{1}$3/Nb$_{2}$3/) $O_{2}$ to BaTi $O_{3}$-3Ti $O_{2}$ resulted in the formation of Ba $Ti_{4}$$O_{9}$, $Ba_{2}$ $Ti_{9}$ $O_{20}$, Ba(Zn$_{1}$3/Nb$_{2}$3/) $O_{3}$, and Ti $O_{2}$ phases. Ba $Ti_{4}$$O_{9}$ phase was gradually transformed to $Ba_{2}$ $Ti_{9}$ $O_{20}$. This was identified by XRD and microstructure. As the Ba $Ti_{4}$$O_{9}$ phase transformed to $Ba_{2}$ $Ti_{9}$ $O_{20}$ phase, the dielectric constant increased to 37.5. Q*f$_{o}$ value was 40000 at x=0.04, and the temperature coefficient of resonant frequency was +10ppm/.deg. C.C.. C.C.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.133-133
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• 2016

화학저항식(Chemiresistive) 가스센서의 저항변화를 향상시키기 위해서는 센서 소재의 비표면적을 향상시키는 방향 및 전자천이를 증가시키는 방향으로 연구가 진행되어야 하며, 그 중 센서의 비표면적을 향상시키는 예로써 중공 나노섬유가 있을 수 있다. 본 연구에서는 비표면적의 향상뿐만 아니라 중공 나노섬유의 전자천이를 증가시켜 센서의 검출 성능을 더욱 향상시키기 위한 목적으로 $TiO_2/ZnO$ 이중층 중공 나노섬유를 제안하었다. 제안된 $TiO_2/ZnO$ 이중층 중공 나노섬유는 템플레이트 합성법을 통해 제작되었으며, 그 공정은 다음과 같다; 전기방사(Electrospinning) 공정을 통해 폴리머 나노섬유를 제작한 후 $TiO_2$ 층과 ZnO 층을 ALD(Atomic Layer Deposition) 공정을 통해 차례대로 증착시킨다. 그 후 후열처리 공정을 통해 코어 폴리머를 제거함으로써 $TiO_2/ZnO$ 이중층 중공 나노섬유를 얻을 수 있다. 이 때, ZnO 층의 두께는 각각 달리하여 제작되었으며, 최종적으로 이들에 대한 가스 센싱 특성 및 메커니즘에 대한 체계적인 조사를 진행하였다. 단층 중공나노섬유는 셀 층의 두께가 Debye length와 유사할 때 셀 층 표면이 완전공핍층이 형성되고, 그 보다 크게 되면 부분적인 공핍층이 형성되게 되어 감응도가 감소하게 된다. 그러나 이중층 중공 나노섬유의 경우 셀 층의 두께가 Debye length 보다 더 크게 되더라도 TiO2와 ZnO의 헤테로접합으로 인해 ZnO에서 TiO2로 전자의 이동을 야기시키게 되어 환원성 가스에 대한 감응도가 단층 ZnO 중공 나노섬유에 비해 향상되게 된다.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1257-1261
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• 1994

Phsysical and dielectric properties of $(1-x)CaTiO_3-xLa(Zn_{1/2}Ti_{1/2})O_3$ ceramics were investigated at the temperature range of $25^{\circ}C$ to $80^{\circ}C$ at the frequency of 6 GHz. As increasing addition of the amount of $La(Zn_{1/2}Ti_{1/2})O_3$ to x = 5 mol,Q value was increased due to grain growth and increase of density. For more addition, Q value decreased due to electrical defect. Temperature coefficient of resonant frequency could be controlled by the amount of $La(Zn_{1/2}Ti_{1/2})O_3$, which could be explained by volume mixing rule.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1019-1023
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• 1996

The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.321-324
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• 2003

The effects of various sintering additives such as $Bi_2O_3+V_2O_5$, $BiVO_4$, $B_2O_3$, and $CuO+V_2O_5$ on the low-temperature sintering and microwave dielectric properties of $(ZnMg)TiO_3$ system were studied. Sintering was enhanced by the sintering additives and highly dense samples were obtained for $(Zn_{0.8}Mg_{0.2})TiO_3$ at the sintering temperature of $910^{\circ}C$. $(Zn_{0.8}Mg_{0.2})TiO_3$ with 6.19 mol.%$B_2O_3$ was found to show the best sintering and microwave dielectric properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.397-403
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• 2003

Microwave dielectric properties of (1-x)ZnW $O_4$-xTi $O_2$ ceramic systems were investigated with calcination temperatures and Ti $O_2$ contents. The ZnW $O_4$ ceramic could be suitably sintered at 1075$^{\circ}C$ and showed the dielectric constant of 13.6, quality factor(Q$\times$ $f_{O}$value) of 22,000 and temperature coefficient of resonant frequency($\tau$$_{f}$) of -65$\pm$2ppm/$^{\circ}C$. Increasing the amount of Ti $O_2$ in the range of 0.25 to 0.45 mol, the dielectric constant and $\tau$$_{f}$ increased due to the role of Ti $O_2$ but the quality factor decreased due to the increase of phase boundaries. The 0.7ZnW $O_4$-0.3Ti $O_2$ ceramic showed the dielectric constant of 19.8, qualify factor(Q$\times$ $f_{0}$) of 20,000 and $\tau$$_{f}$ of -3$\pm$1ppm/$^{\circ}C$.>.EX>.>.>.