• Korean Journal of Materials Research
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• v.3 no.5
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• pp.497-504
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• 1993

Effects of $Ta_2O_5,ZrO_2$ and $SiO_2$ addition on magnetic properties of 0.02wt%$Bi_2O_3$ and 0 . 0 5 wt%$CaCO_3$ doped Mn-Zn ferrites(58.5mol% $Fe_2O_3$, 25.5 mol% ZnO) were investigated. E:lectrlcal resistivity and magnetic properties such as the initial permeability($\mu_i$), loss factor(tan$\delta$), coercive force Hc(m0c) were measured. With lncreasing $Ta_2O_5$ and $ZrO_2$ addition, the following effects were observed: I ) Decreasing of the average grain size; 2) lncreasing of the electrical resistivity and initial permeability; 3) Ilecreasmg of loss factor values. (very low loss esprcially at high frequency region) ; 4 ) Fine and uniform microsrructures were obtamed at O.lwt% nddecl samples. In case of $SiO_2$ addition, anomalous grain growth and degradation of magnetic properties were observed. The obtained maximum initial permeability value was 6260 at IOkHz. $25^{\circ}C$ from 0.02wt%$Bi_2O_3$. 0.05wt%$CaCO_3$, 0.lwt%$Ta_2O_5$ added sample, the corresponded relative loss factor (tan$\delta /\mu_i$)for the sample was $4.2 \times 10^{-6}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.883-888
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• 2007

Investigation of improving the properties of UV detector which uses the wide bandgap of ZnO are under active progress. The present study focused on the design and fabrication of i-ZnO/p-inversion $layer/n^--Si$ Epi. which is characterized with very thin p-type inversion layer for UV detectors. The i-ZnO thin film for achieving p-inversion layer which was grown by RF sputtering at $450^{\circ}C$ and then annealed at $400^{\circ}C$ in $O_2$ gas for 20 min shows good intrinsic properties. High (0002) peak intensity of the i-ZnO film is shown on XRD spectrum and it is confirmed by XPS analysis that the ratio of Zn : O of the i-ZnO film is nearly 1 : 1. Measurement shows high transmission of 79.5 % in UV range (< 400 nm) for the i-ZnO film. Measurement of $V_r-I_{ph}$ shows high UV photo-current of 1.2 mA under the reverse bias of 30 V.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.137-143
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• 2010

Oxide semiconductors Thin-film transistors are an exemplified one owing to its excellent ambient stability and optical transparency. In particular zinc oxide (ZnO) has been reported because It has stability in air, a high electron mobility, transparency and low light sensitivity, compared to any other materials. For this reasons, ZnO TFTs have been studied actively. Furthermore, we expected that would be satisfy the demands of flexible display in new generation. In order to do that, ZnO TFTs must be fabricated that flexible substrate can sustain operating temperature. So, In this paper we have studied low-temperature process of zinc oxide(ZnO) thin-film transistors (TFTs) based on silicon nitride ($SiN_x$)/cross-linked poly-vinylphenol (C-PVP) as gate dielectric. TFTs based on oxide fabricated by Low-temperature process were similar to electrical characteristics in comparison to conventional TFTs. These results were in comparison to device with $SiN_x$/low-temperature C-PVP or $SiN_x$/conventional C-PVP. The ZnO TFTs fabricated by low-temperature process exhibited a field-effect mobility of $0.205\;cm^2/Vs$, a thresholdvoltage of 13.56 V and an on/off ratio of $5.73{\times}10^6$. As a result, We applied experimental for flexible PET substrate and showed that can be used to ZnO TFTs for flexible application.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1340-1342
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• 2001

ZnO thin films are Prepared on Si(111) substrate by RF magnetron sputtering. Two-step deposition method is proposed to obtain ZnO thin films with high c-axis (002) TC value and electrical resistivity. This method consists of the following two-step deposition procedures: 1st-deposition for 10$\sim$30 min without oxygen at 100W and 2nd-deposition with oxygen added in the range of $O_2/(Ar+O_2)$ = 10 $\sim$ 50%. SAW filters with IDT/ZnO/Si(111) configuration are also fabricated. From the frequency response characteristics, the insertion loss and the side-lobe rejection are estimated.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.259-264
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• 2010

In continuous hot dip galvanizing process, oxide formation on steel surface has an influence on Zn wetting. High strength automotive steel contains high amount of Si and Mn, where Si-Mn composite oxides such as $Mn_2SiO_4$ or $MnSiO_3$ covers the surface after annealing. Zn wetting depends on how the aluminothermia reaction can reduce the Mn-Si composite oxides and then form inhibition layer such as $Fe_2Al_5$ on the steel surface. The outward diffusion of metallic ions such as $Mn^{2+}$, $Si^{2+}$ in the steel matrix is very important factor for the formation of the surface oxides on the steel surface. The surface state and grain boundaries provide an important role for the diffusion and the surface oxide reactions. Some elements such as P, Sb, and B have a strong affinity for the interface precipitation, and it influence the diffusivity of metallic ions on grain boundaries. B oxide forms very rapildly on the steel surface during the annealing, and this promote complex oxides with $SiO_2$ or MnO. P has inter-reacted with other elements on the grain boundaries and influence the diffusion through on them. Small addition of Sb could suppress the decarburization from steel surface and retards the formation of internal and external selective oxides on the steel surface. Interface control by the trace elements such as Sb could be available to improve the Zn wettability during the hot dip galvanizing.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.191.2-191.2
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• 2013

The negative photoconductivity was frequently observed in some semiconductors. It was known that the origin of the negative photoresponse from ZnO is molecular chemisorption or the charging effect of nanoparticles in bulk matrix. However, the origin of the negative photoresponse of thin film was not still clear. One of possible explanation is due to the deep level trap scheme, which describes the origin of the negative photoresponse via defect state under illumination of light. However, the defect states below Fermi level have high capture rate by Coulomb effect, so that these states are usually filled by electrons if the defect states have donor-like character. Therefore the condition which the defect states located in below Fermi level should be partially filled by electrons make more difficult to understand of mechanism of the negative photoresponse. In this study, n-ZnO/p-Si heterojunction diodes were fabricated by UHV RF magnetron sputter. Then, some diodes show the negative photoresponse under ultra-violet light illumination. The defect state of the ZnO was analyzed by photoluminescence and deep level transient spectroscopy. To interpret the negative photoconductivity, band diagram was simulated by using SCAPS program.

• Korean Journal of Crystallography
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• v.2 no.2
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• pp.1-6
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• 1991

ZnO thin films were deposited on p-Si(100) and Coming glass 7059 by f magnetron sputtering mothod. The effect of deposition parameters on the electrical, structural and optical properties were investigated. Highly c-axis oriented ZnO thin films were deposited at high rf power. Standard deviation(σ) of X-ray rocking curve of peak at 26θ=34,4˚ ranged from 6.8˚ to 7.2˚, depending on the deposition condition. ZnO thin films deposited on glass substrate eihibited 80% transmittance in the visible range, regardless of the deposition parameters. Resistivity of ZnO thin films was significantly affected by f power and Ar pressure, and ranged widely from 3×102 to 2×109 Ω.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.178-183
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• 2002

Zinc fluosilicate ($ZnSiF_6$, 15% aqueous solution) was prepared using zinc oxide (ZnO) and fluosilicic acid ($H_2SiF_6$) by soluiton synthetic method. The fluidity and hydration properties of cement which was added $ZnSiF_6$ (aq.) as an additive for cement were studied. At water to cement ratio (W/C) equals to 0.45, the initial fluidity and slump loss of cement paste which the addition of $ZnSiF_6$ (aq.) was increased from 1.0% to 4.0% based on cement weight were investigated. Initial fluidity of cement paste was measured by mini-slump test and slump loss was examined by measuring the fluidity variation of cement paste with time elapsed from 0 min to 120 min at intervals 30 min. Also, the effect of $ZnSiF_6$ addition on the setting and hydration of cement paste when $ZnSiF_6$ increased in the addition range 1.0% to 3.0% were investigated. The fluidity of cement paste which was added 2.1% $ZnSiF_6$ (aq.) presented the highest value among all addition ranges. The setting time of cement paste was retarded gradually and the heat evolution of hydrated cement was reduced with the increasing of $ZnSiF_6$ addition.

• New & Renewable Energy
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• v.3 no.4
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• pp.63-68
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• 2007

유리를 기판으로 하는 superstrate pin 비정질 실리콘 태양전진에서 전면 투명전도막(TCO)과 p-층의 계면은 태양전지 변환효율에 큰 영향을 미친다. 면투명전도막(TCO)으로 현재 일반적으로 사용되는 ZnO:Al는 $SnO_2:F$보다 전기, 광학적으로 우수하고, 안개율 (Haze)높으며, 수소 플라즈마에서 안정성이 높은 특징을 갖고 있다. 그래서 박막 태양전지의 특성향상에 매우 유리하나, 태양전지로 제조했을 때, $SnO_2$보다 충진율(Fill Factor:F.F)과 $V_{oc}$가 감소한다는 단점을 가지고 있다. 본 실험실에서는 $SnO_2:F$dml F.F.가 72%이 나온 반면 ZnO:Al의 F.F은 68%에 그쳤다. 이들 원인을 분석하기 위해 TCO/p-layer의 전기적 특성을 알아 본 결과, $SnO_2:F$보다 ZnO:Al의 직렬저항이 높게 측정되었다. 이러한 결과를 바탕으로 p-layer에 $R=(H_2/SiH_4)=25$로 변화, p ${\mu}c$-Si:H/p a-SiC:H로 p-layer 이중 증착, p-layer의 boron doping 농도를 증가시키는 실험을 하였다. 직렬저항이 가장 낮았던 p ${\mu}c$-Si:H/p a-SiC:H 인 p-layer 이중 증착에서 $V_{oc}$는 0.95V F.F는 70%이상이 나왔다. 이들 각 p층의 $E_a$(Activiation Energy)를 구해본 결과, ${\mu}c$-Si:H의 Ea 가 가장 낮은 것을 관찰 할 수 있었다.

• Korean Journal of Materials Research
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• v.14 no.9
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• pp.670-675
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• 2004

Glasses in the $Bi_{2}O_3-SiO_2-ZnO$ glasses system were examined as a potential replacement for lead-oxide glass frits with low firing temperature ($500\sim600^{\circ}C$) for the dielectric layer of a plasma display panel (PDP). The glasses were evaluated for glass transition temperature($T_{g}$) and thermal expansion coefficient(${\alpha}$). After forming transparent thick films by a screen-printing method, it was evaluated for the optical properties. The transmittance of thick films fired at $500-600^{\circ}C$ showed above $80\%$, which was not dependent on the firing temperature. As a result, many pores were observed at samples fired at low temperature, while the number of pores from samples prepared at high temperature decreased and the pores size increased.