• 한국재료학회지
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• 제6권1호
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• pp.40-48
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• 1996

고주파 저손실 재질로 사용되고 있는 Mn-Zn 페라이트의 제조공정 중 소결조건과 Ta2O5첨가가 Mn-Zn 페라이트의전력손실에 미치는 영향에 대해서 연구하였다. 등조성선을 따라 냉각하기 위하여 컴퓨터를 사용해서 정확하게 산소분압을 조절하였으며 적절한 등조성선을 선택함으로써 보다 좋은 손실특성을 얻을 수 있었다. CaO-SiO2 첨가계에 Ta2O5를 0ppm에서 400ppm으로 변화시켜 가며 첨가하였으며, Ta2O5 가 400ppm 첨가되었을 경우 균일한 grain 성장과 더불어 낮은 전력손실을 나타내었다. 온도에 상응하는 상평형 산소분압을 정확히 맞춰 냉각할 경우 전력손실 최소값이 질소 분위기에서 냉각시킨 시편보다 높은 온도쪽으로 이동됨도 확인할 수 있었다.

• 한국재료학회지
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• 제18권12호
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• pp.655-659
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• 2008

The NO gas sensing properties of ZnO-carbon nanotube (ZnO-CNT) composites fabricated by the coaxial coating of single-walled CNTs with ZnO were investigated using pulsed laser deposition. Upon examination, the morphology and crystallinity of the ZnO-CNT composites showed that CNTs were uniformly coated with polycrystalline ZnO with a grain size as small as 5-10 nm. Gas sensing measurements clearly indicated a remarkable enhancement of the sensitivity of ZnO-CNT composites for NO gas compared to that of ZnO films while maintaining the strong sensing stability of the composites, properties that CNT-based sensing materials do not have. The enhanced gas sensing properties of the ZnO-CNT composites are attributed to an increase in the surface adsorption area of the ZnO layer via the coating by CNTs of a high surface-to-volume ratio structure. These results suggest that the ZnO-CNT composite is a promising template for novel solid-state semiconducting gas sensors.

• 한국자기학회지
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• 제16권4호
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• pp.201-205
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• 2006

$(Ni_{0.2}Cu_{0.2}ZnO_{0.2})_{1.02}(Fe_{2}O_{3})_{0.98}$의 기본 조성에 첨가제 $Bi_2O_3$와 $ZrO_2$ 첨가량과 소결 온도를 변화시켜 시편의 전자기적 특성 및 미세 구조를 조사하였다. 그 결과 XRD pattern을 통하여 완전한 spinel 구조를 가짐을 확인 할 수 있었으며 소결 온도와 첨가제의 양의 증가에 따라 소결 밀도, 입자 크기가 증가 하였으며, 소결 온도가 증가하고 첨가제의 양이 감소할수록 시편의 투자율이 크게 관찰되었다. 또한, $Bi_2O_3$의 첨가가 입자의 크기와 투자율 변화등 전자기적 특성에 더욱 더 많은 영향을 미치는 것으로 조사되었다.

• 한국전기전자재료학회논문지
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• 제13권6호
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• pp.493-501
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• 2000

The microstructure and electrical properties of ZnO-Pr$_{6}$/O$_{11}$-CoO-Er$_{2}$/O$_{3}$ based varistors were investigated with Er$_{2}$/O$_{3}$ additive content of the range 0.0 to 2.0 mol%. Most of the added Er$_{2}$/O$_{3}$ were segregated at the nodal points and grain boundaries and it coexisted with Pr$_{6}$/O$_{11}$ in the bulk intergranular layer. The average grain size was decreased in the range of 7.44 to 5.62${\mu}{\textrm}{m}$ at 130$0^{\circ}C$ and 18.36 to 9.11 at 135$0^{\circ}C$ with increasing Er$_{2}$/O sub 3/ additive content. The density of ceramics was in the range 4.87 to 5.08 g/cm$^3$ at 130$0^{\circ}C$ and 5.35 to 5.62 g/cm$^3$at 135$0^{\circ}C$. At 130$0^{\circ}C$ the varistors without Er$_{2}$/O$_{3}$ exhibited 29.66 in the nonlinear exponent and 28.23 $\mu$A in the leakage current whereas the varistors with 0.5 mol% Er$_{2}$/O$_{3}$ exhibited a high nonlinearity which is 52.78 in thenonlinear exhibited and 9.75 $\mu$A in the leakage current. At 135$0^{\circ}C$ the varistors without Er$_{2}$/O$_{3}$ exhibited a very poor nonlinearity indicating 2.08 in the nonlinear exponent and 133.79 $\mu$A in the leakage current whereas the varistors with 1.0mol% Er$_{2}$/O$_{3}$ exhibited a relatively high nonlinearity which is 36.79 in the nonlinear exponent and 5.92 $\mu$A in the leakage current. Therefore Er$_{2}$/O$_{3}$ was additive which greatly improve the nonlinearity. It is believed that ZnO-0.5 mol% Pr$_{6}$/O$_{11}$-1.0 mol% CoO-0.5 mol% Er$_{2}$/O$_{3}$ based ceramicss will be usefully used as a basic composition to develop the advanced pr$_{6}$/O$_{11}$-based ZnO varistors.ristors.ristors.

• 한국자기학회지
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• 제11권1호
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• pp.26-31
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• 2001

MoO$_3$의 첨가가 Mn-Zn ferrites의 투자율에 미치는 효과를 고찰하였다. 하소 후 분쇄과정에서 MoO$_3$를 각각 600 ppm, 800ppm, 1,000pp으로 첨가하였다. 소결은 135$0^{\circ}C$에서 3시간 동안 수행하였으며 냉각시 산소분압을 조절하였다. 승온속도를 분당 5$^{\circ}C$로 했을 경우 MoO$_3$를 첨가하지 않은 시편의 경우 8,000정도의 초기투자율 값을 나타내었고 MoO$_3$를 600 ppm, 800 ppm 첨가한 시편에서는 초기투자율의 값이 13,200, 13,550으로 증가하였다. 그러나 1,000 ppm 첨가한 경우에는 1,00$\mu\textrm{m}$ 이상의 과대입성장이 관찰되었으며 초기투자율 값 또한 감소하였다. 반면에 승온속도를 분당 1$0^{\circ}C$로 변화한 시편의 경우 MoO$_3$첨가량이 1,000ppm일 때 과대입성장이 관찰되지 않았고 초기투자율이 15,000 이상의 높은 값을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.9-9
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• 2009

1 wt % Ga-dope ZnO (ZnO:Ga) thin films with n-type semiconducting behavior were grown on c-sapphire substrates by radio frequency magnetron sputtering at various growth temperatures. The room temperature grown ZnO:Ga film showed the faint preferred orientation behavior along the c-axis with small domain size and high density of stacking faults, despite limited surface diffusion of the deposited atoms. The increase in the growth temperature in the range between $300\sim550^{\circ}C$ led to the granular shape of epitaxial ZnO:Ga films due to not enough thermal energy and large lattice mismatch. The growth temperature above $550^{\circ}C$ induced the quite flat surface and the simultaneous improvement of electrical carrier concentration and carrier mobility, $6.3\;\times\;10^{18}/cm^3$ and $27\;cm^2/Vs$, respectively. In addition, the increase in the grain size and the decrease in the dislocation density were observed in the high temperature grown films. The low-temperature photoluminescence of the ZnO:Ga films grown below $450^{\circ}C$ showed the redshift of deep-level emission, which was due to the transition from $Zn_j$ to $O_i$ level.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.64-67
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• 2000

Element distribution analysis and degradation characteristics of the ZnO varistors fabricated at the ambient sintering-process is investigated in this study. ZnO varistors made of Matsuoka's composition were fabricated by standard ceramic techniques. The ambient sintering-process is performed at the special electrical-furnace which is equipped with the vacuum system. The Gases of injection at sintering- process were oxygen, air, nitrogen and argon respectively. Element and quantitative analysis in the microstructure of ZnO varistors made use of EPMA equipment. Degradation characteristics were showed by DC degradation tests at $115{\pm}2\;^{\circ}C$ for period up to 13 h. From above analysis, it is found that at the DC degradation test the ZnO varistor sintered in oxygen atmosphere showed the excellent prop properties among them and these results could be explain by element and quantitative analysis in ZnO microstructure.

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.208-210
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• 2013

ZnO films were deposited on glass substrates by radio frequency (RF) magnetron sputtering and exposed to intense electron beam irradiation to investigate the effects of electron irradiation on the properties of the films. Although all of the films had ZnO (002) textured structure regardless of electron irradiation, the grain sizes of the films decreased with electron irradiation. Surface roughness also depended on electron irradiation. The surface roughness varied between 2.3 and 1.6 nm, depending on the irradiation energy. Based on photoluminescence (PL) characterization, the most intense UV emission was observed from ZnO films irradiated at 900 eV. Since the intensity of UV emission is dependent upon the stoichiometric of ZnO films, we conclude that 900 eV was the optimum electron irradiation energy to achieve the best stoichiometric of ZnO films in this study.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.145-145
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• 2010

It is observed from SEM images that many voids were created after annealed by helium gas. The PL spectra of the ZnO samples revealed the strong violet emission peaks at 3.05 eV with the relative weak near band edge UV emissions. It was concluded from experiment results that native $Zn_i$ and $V_o$ donor defect levels can be generated below the conduction band edge due to the incorporation of helium atoms decomposed from helium gas into the ZnO matrix. He atoms in ZnO matrix will affect the interface trap existing in depletion regions located at the grain boundaries, which leads to the creation of $Zn_i$ and $V_o$ donor defect levels.

• 반도체디스플레이기술학회지
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• 제9권1호
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• pp.29-33
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• 2010

Recently, the growth of ZnO thin film on glass substrate has been investigated extensively for transparent thin film transistor. We have studied the phase transition of ZnO thin films from metal to semiconductor by changing RF power in the deposition process by RF magnetron sputtering system. The structural, electric, and optical properties of the ZnO thin films were investigated. The film deposited with 75 watt of RF power showed n-type semiconductor characteristic having suitable resistivity $-3.56\;{\times}\;10^{+1}\;{\Omega}cm$, carrier concentration $-2.8\;{\times}\;10^{17}\;cm^{-3}$, and mobility $-0.613\;cm^2V^{-1}s^{-1}$ while other films by 25, 50, 100 watt of RF power closed to metallic films. From the surface analysis (AFM), the number of crystal grain of ZnO thin film increased as RF power increased. The transmittance of the film was over 88% in the visible region regardless of the change in RF power.