• Korean Journal of Materials Research
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• v.19 no.5
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• pp.259-264
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• 2009

In this study we investigated the effect of the multi-step texturing process on the electrical and optical properties of hydrogenated Al-doped zinc oxide (HAZO) thin films deposited by rf magnetron sputtering. AZO films on glass were prepared by changing the $H_2/(Ar+H_2)$ ratio at a low temperature of $150^{\circ}C$. The prepared HAZO films showed lower resistivity and higher carrier concentration and mobility than those of non-hydrogenated AZO films. After deposition, the surface of the HAZO films was multi-step textured in diluted HCl (0.5%) for the investigation of the change in the optical properties and the surface morphology due to etching. As a result, the HAZO film fabricated under the type III condition showed excellent optical properties with a haze value of 52.3%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.362-365
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• 2002

Hf thin films were deposited on bottom metal using a RF magnetron sputtering method followed by oxidation and annealing in O$_2$ and N$_2$ ambient, respectively. Various top metal electrodes (i.e., Al, Au, and Cu) were deposited by evaporation, and their roles on physical and electrical properties were investigated. Using the XRD, SEM and AFM techniques, we confirmed that the grain size of HfO$_2$ thin films enlarges as a function of oxidation temperature, increasing dielectric constant. However, other electrical properties (e.g., tan) deteriorateas a consequence. The dielectric constant and tan of HfO$_2$ thin films oxidized at 500 $^{\circ}C$ were 17-25 and 3${\times}$10-3 - 2x10-2, respectively, in the frequency range of 1 Hz to 1 MHz. The leakage current density was less than 1${\times}$10-8A/cm2 up to 0.7 MV/cm. In addition, electrical properties of HfO$_2$ thin films (e.g., the dielectric constant, leakage current and tan $\delta$) depend on top metal electrode. We showed that Al top metal electrode results in the best result.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.318-321
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• 2009

We have studied transparent top gate Al-Zn-Sn-O (AZTO) TFTs with an $Al_2O_3$ protective layer (PL) on an active layer. We also fabricated a transparent 2.5 inch QCIF+AMOLED display panel using the AZTO TFT back-plane. The AZTO active layers were deposited by RF magnetron sputtering at room temperature and the PL was deposited by ALD with two different processes. The mobility and subthreshold slope were superior in the cases of the vacuum annealing and the oxygen plasma PL compared to the $O_2$ annealing and the water vapor PL, however, the bias stability was excellent for the TFTs of the $O_2$ annealing and the water vapor PL.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.133-133
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• 2011

최근 나노입자를 이용한 비휘발성 메모리 소자의 제작에 대한 연구가 진행되고 있다. 특히, 실리사이드 계열의 나노입자를 적용한 소자는 일함수가 크지만 실리콘 내의확산 문제를 가지고 있는 금속 나노입자와 달리 현 실리콘 기반의 반도체 공정 적용이 용이한 잇 점을 가지고 있다. 따라서 본 연구에서는 실리사이드 계열의 화합물 중에서 4.63 eV인 Vanadium Silicide ($V_3$Si) 박막을 열처리 과정을 통하여 수 nm 크기의 나노입자로 제작하였다. 소자의 제작은 p-Si기판에 5 nm 두께의 $SiO_2$ 터널층을 dry oxidation 방법으로 성장시킨 후 $V_3$Si 금속박막을 RF magnetron sputtering system을 이용하여 3~5 nm 두께로 tunnel barrier위에 증착시켰다. Rapid thermal annealing법으로 질소 분위기에서 $1000^{\circ}C$의 온도로 30초 동안 열처리하여 $V_3$Si 나노 입자를 형성 하였으며. 20 nm 두께의 $SiO_2$ 컨트롤 산화막층을 ultra-high vacuum magnetron sputtering을 이용하여 증착하였다. 마지막으로 thermal evaporation system을 통하여 Al 전극을 직경 200, 두께 200nm로 증착하였다. 제작된 구조는 metal-oxide-semiconductor구조를 가지는 나노 부유 게이트 커패시터 이며, 제작된 시편은 transmission electron microscopy을 이용하여 $V_3$Si 나노입자의 크기와 균일성을 확인했다. 소자의 전기적인 측정은 E4980A capacitor parameter analyzer와 Agilent 81104A apulse pattern generator system을 이용한 전기용량-전압 측정을 통해 전하저장 효과를 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.117-117
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• 1999

최근 광소자와 더불어 발전과 더불어 고효율의 새로운 광소자에 대한 수요가 증가되고 있다. ZnO는 이러한 특성을 가진 재료중에 한가지로서 최근 들어 그 가능성에 대한 연구가 활발히 이루어지고 있다. 특히 상온에서 exciton binding energy가 다른 재료보다 큰 60meV로 고효율의 blue, UV 발광이 가능한 재료로 알려져 있다. 본 연구에서도 광소자로서 ZnO를 활용하기 위해서 RF magnetron sputtering법을 이용하기 위하여 광특성의 향상에 목적을 두고 연구하였다. ZnO 박막은 RF magnetron sputtering법을 이용하여 sapphire (0001) 기판위에 성장시켰다. RF power는 60W에서 120W까지 변화시켰고 박막의 성장온도는 55$0^{\circ}C$와 $600^{\circ}C$로 변화시켰으며, 박막의 성장시간은 60분, ZnO target과 기판과의 거리는 4.5cm로 하여 성장시켰다. 성장된 ZnO 박막은 XRD $\theta$-rocking scan 측정을 통해서 박막의 C-축 배향성과 RBS channeling를 이용하여 ZnO 박막의 epitaxial 성장 정도를 측정하였다. 박막의 상온 발광 특성은 He-Cd laser를 사용한 photoluminescence spectra로 측정하였다. 또한 표면의 morphology는 atomic force microscope(AFM)를 이용하여 관찰하였으며 transmission electron microscopy(TEM)을 사용하여 ZnO박막의 단면적을 관찰함으로서 grain의 성장과 광특성 및 결정성과의 영향에 대해서 연구하였다. ZnO 박막의 성장온도 55$0^{\circ}C$에서 RF power를 60W에서 120W까지 변화시킬 경우 XRD $\theta$-rocking peak의 반치폭이 0.157$^{\circ}$에서 0.436$^{\circ}$까지 변화하였고 80W에서 최소값을 가졌으며 in-plain에 대한 XRD 측정 결과 ZnO 박막의 성장은 sapphire 기판에 대해서 30$^{\circ}$회전되어 성장된 것으로 알 수 있었으며 이는 ZnO [100]∥ Al2O3[110]의 관계를 갖는다는 것을 나타낸다. 광특성의 측정 결과인 PL peak의 반치폭은 133.67meV에서 89.5meV까지 변화함을 알 수 있었고 80W에서 최대값을 가졌으며 이는 RF power의 변화에 따른 결정성의 변화와는 반대되는 현상임을 알 수 있었다. 그러나 성장온도 $600^{\circ}C$일때에는 XRD $\theta$-rocking peak의 반치폭이 0.129$^{\circ}$로 결정성이 우수한 박막임을 확인할 수 있었고 PL peak의 반치폭 또한 Ar과 O2의 비율에 따라 76.32meV에서 98.77meV로 광특성도 우수한 것으로 나타났다. RBS channeling 결과 55$0^{\circ}C$에서는 $\chi$min값이 50~60%였으나 $600^{\circ}C$일 때에는 $\chi$min값이 4~5%로 박막이 epitaxial 성장을 하였다는 것을 알 수 있었다. 결정성과 광특성과의 연관성을 알아보기 위해 TEM을 이용한 박막의 cross section image를 관찰한 결과 광특성이 우수한 시편일수록 grain의 크기가 큰 것으로 나타났고 결정성이 우수한 시편의 경우에서는 XRD분석 결과에서처럼 C-축배향성이 우수한 것을 확인할 수 있었다. 이상의 결과로부터 RF magnetron sputtering 법으로 광특성이 우수한 양질의 ZnO박막 성장이 가능하였다는 것을 알 수 있었으며 광소자로써의 가능성을 확인 할 수 있었다.

• Journal of the Korean institute of surface engineering
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• v.55 no.5
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• pp.284-291
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• 2022

Herein, we studied ultrathin Cu-layer-based transparent heaters embedded between a ZnO underlayer and an Al₂O₃ overlayer. The anti-reflecting functions for the ZnO and Al₂O₃ layers by independently varying the layer thicknesses, with the Cu layer thickness fixed at 8.5 nm. The smallest visible light transmittance of 11.1% was achieved when the overlayer and underlayer thicknesses were 90 and 30 nm, respectively. We conducted electrically driven Joule heating test for the Cu layers having thicknesses of 8.5 nm (R_s: 14.7 Ohm/sq.) and 19 nm (R_s: 3.4 Ohm/sq.). External voltages were increased with an interval of 2 V until irreversible failures occurred at temperatures of ~390 ℃ and 550 ℃, respectively. At each voltage increase before heater failures, the heater exhibited superior thermal response with the heater temperatures reaching over 90% of the final temperatures. The heaters also showed excellent reproducibility when turning on and off the heater repeatedly.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.2
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• pp.157-163
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• 1996

To ceramic film, $SiO_2$ and $Al_2O_3$, coated on pure Fe and stainless steel(SUS41O) by RF magnetron sputtering, the adherence between mm and substarte was studied. The adherence index (${\chi}$) was determined by the measure of micro hardness test. Also, the corrosion resistance on oxide coatings was studied using electrochemical measurement. The main results obtained are as the following: 1) In the micro-hardness test, with $1{\mu}m$ thickness mm, it has only one the value of ${\chi}$. Above $2{\mu}$thickness fIlm, however, get another value of ${\chi}$as the cracks in fIlm. 2) The oxide fIlm adhere well on the mild materials such as pure steel than high intensity materials like stainless. 3) Alumina($Al_2O_3$) coated materials have better corrosion resistance than silica($SiO_2$)coated materials

• Korean Journal of Materials Research
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• v.16 no.6
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• pp.346-350
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• 2006

Al-doped ZnO (AZO) thin films were grown on type of glass#1737 substrates by DC magnetron sputtering. The structural, electrical and optical properties of the films were investigated as a function of various plasma discharge power. The obtained films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The lowest resistivity was $6.0{\times}10^{-4}{\Omega}cm$ with the carrier concentration of $2.69{\times}10^{20}cm^{-3}$ and Hall mobility of 20.43 $cm^2/Vs$. The average transmittance in the visible range was above 90%.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.08a
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• pp.98-98
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• 2007

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.194-197
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• 2013

We investigated the effect of etching time on the surface roughness, and electrical and optical properties of ZnO and 2 wt% Al-doped ZnO (AZO) films. The ZnO and AZO films were deposited on glass substrates by RF magnetron sputtering technique. The etching experiment was carried out using a solution of 5% HCl at room temperature. The surface roughness was characterized by Atomic Force Microscopy. The electrical property was measured by Hall measurement system and 4-point probe. The optical property was characterized by UV-vis spectroscopy. After the wet chemical etching, the surface textures were obtained on the surface of the ZnO and AZO films. With the increase of etching time, the surface roughness (RMS) of the films increased and the transmittance of the films was observed to decrease. For the AZO film, a low resistivity of $1.0{\times}10^{-3}\;{\Omega}{\cdot}cm$ was achieved even after the etching.