• 한국재료학회지
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• 제29권3호
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• pp.196-203
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• 2019

We report on the fabrication and characterization of an oxide photoanode with a zinc oxide (ZnO) nanorod array embedded in cuprous oxide ($Cu_2O$) thin film, namely a $ZnO/Cu_2O$ oxide p-n heterostructure photoanode, for enhanced efficiency of visible light driven photoelectrochemical (PEC) water splitting. A vertically oriented n-type ZnO nanorod array is first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type $Cu_2O$ thin film is directly electrodeposited onto the vertically oriented ZnO nanorod array to form an oxide p-n heterostructure. The introduction of $Cu_2O$ layer produces a noticeable enhancement in the visible light absorption. From the observed PEC current density versus voltage (J-V) behavior under visible light illumination, the photoconversion efficiency of this $ZnO/Cu_2O$ p-n heterostructure photoanode is found to reach 0.39 %, which is seven times that of a pristine ZnO nanorod photoanode. In particular, a significant PEC performance is observed even at an applied bias of 0 V vs $Hg/Hg_2Cl_2$, which makes the device self-powered. The observed improvement in the PEC performance is attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential including the light absorption and separation processes of photoinduced charge carriers, which provides a new avenue for preparing efficient photoanodes for PEC water splitting.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.497-502
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• 2019

금속산화물 나노구조물은 고감도 가스센서 및 대용량의 리튬이온 전지와 같은 첨단 응용 분야에 활용될 수 있는 유망한 소재로 알려져 있다. 본 연구에서는 산화주석(SnO) 나노구조물을 두 영역 전기로 장치를 이용하여 다양한 온도에서 Si 웨이퍼 기판 위에 성장시켰다. 원료물질인 이산화주석($SnO_2$) 파우더를 알루미나 도가니 속에 넣어서 $1070^{\circ}C$에서 기상화시켰으며, 이송가스인 고순도 Ar 가스를 1000 sccm으로 흘려주었다. SnO 나노구조물은 $350{\sim}450^{\circ}C$, 545 Pa 조건에서 30분 동안 Si 기판 위에 성장되었다. 성장된 SnO 나노구조물의 표면형상을 전계방출형 주사전자현미경(FE-SEM)과 원자힘 현미경(AFM)으로 조사하였다. 또한 성장된 SnO 나노구조물의 결정학적 특징을 Raman 분광학으로 조사하였다. 그 결과 성장된 산화주석은 SnO 상을 가지고 있었다. 기판의 온도가 증가함에 따라 성장된 SnO 나노구조물의 두께와 결정립의 크기도 $424^{\circ}C$까지는 증가하였다. $450^{\circ}C$에서 성장된 SnO 나노구조물은 복잡한 다결정 형태의 표면형상을 나타내었지만, $350{\sim}424^{\circ}C$ 범위에서 성장된 SnO 나노구조물은 기판에 나란한 형태의 단순한 결정구조를 나타내었다.

• 한국재료학회지
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• 제20권4호
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• pp.175-180
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• 2010

Transparent conducting oxide (TCO) films are widely used for optoelectronic applications. Among TCO materials, zinc oxide (ZnO) has been studied extensively for its high optical transmission and electrical conduction. In this study, the effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films (GZO) on polyethylene naphthalate (PEN) substrate were studied. The $O_2$ plasma pretreatment process was used instead of conventional oxide buffer layers. The $O_2$ plasma treatment process has several merits compared with the oxide buffer layer treatment, especially on a mass production scale. In this process, an additional sputtering system for oxide composition is not needed and the plasma treatment process is easily adopted as an in-line process. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the PEN substrate and the GZO film, the $O_2$ plasma pre-treatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the contact angle decreased and the RMS surface roughness increased significantly. It is believed that the surface energy and adhesive force of the polymer surfaces increased with the $O_2$ plasma treatment and that the crystallinity and grain size of the GZO films increased. When the RF power was 100W and the treatment time was 120 sec in the $O_2$ plasma pretreatment process, the resistivity of the GZO films on the PEN substrate was $1.05\;{\times}\;10^{-3}{\Omega}-cm$, which is an appropriate range for most optoelectronic applications.

• 폴리머
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• 제36권3호
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• pp.393-400
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• 2012

광전소자 유연기판으로 사용되는 폴리에테르설폰(PES) 필름 위에 E beam을 이용하여 저온 증착된 indium tin oxide(ITO) 박막 특성을 살펴보았다. 증착 시 기판 온도가 증가함에 따라 저온 열처리 과정에서 ITO 결정화가 잘 이루어져 면 저항의 감소와 투과도가 증가됨을 알 수 있었다. 증착 시 사용된 산소 가스는 ITO의 결정화를 촉진시켜 면 저항 감소와 투과도 증가에 도움을 줌을 확인하였다. PES 기판 표면 거칠기가 증가될수록 증착된 ITO의 결정화가 잘 이루어지지 않으며 이는 면 저항의 증가 및 투과도의 감소 요인으로 작용함을 알 수 있었다.

• 대한전자공학회논문지SD
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• 제47권4호
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• pp.69-74
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• 2010

알루미늄 양극산화(aluminum anodization)의 선택적인 적용을 통하여 DRAM 소자를 위한 새로운 패키지 기판을 제작하였다. 에폭시 계열의 코어(core)와 구리의 적층 형태로 제작되는 일반적인 패키지 기판과는 달리 제안된 패키지 기판은 아래층 알루미늄(aluminum), 중간층 알루미나(alumina, $Al_2O_3$) 그리고 위층 구리(copper)로 구성된다. 알루미늄 기판에 양극산화 공정을 수행함으로써 두꺼운 알루미나를 얻을 수 있으며 이를 패키지 기판의 유전체로 사용할 수 있다. 알루미나층 위에 구리 패턴을 배치함으로써 새로운 2층 금속 구조의 패키지 기판을 완성하게 된다. 또한 알루미늄 양극산화를 선택적인 영역에만 적용하여 내부가 완전히 채워져 있는 비아(via) 구조를 구현할 수 있다. 패키지 설계 시에 비아 인 패드(via in pad) 구조를 적용하여 본딩 패드(bonding pad) 및 볼 패드(ball pad) 상에 비아를 배치하였다. 상기 비아 인 패드 배치 및 2층 금속 구조로 인해 패키지 기판의 배선 설계가 보다 수월해지고 설계 자유도가 향상된다. 새로운 패키지 기판의 주요 설계인자를 분석하고 최적화하기 위하여 테스트 패턴의 2차원 전자기장 시뮬레이션 및 S-파라미터 측정을 진행하였다. 이러한 설계인자를 바탕으로 모든 신호 배선은 우수한 신호 전송을 얻기 위해서 $50{\Omega}$의 특성 임피던스를 가지는 coplanar waveguide(CPW) 및 microstrip 기반의 전송선 구조로 설계되었다. 본 논문에서는 패키지 기판 구조, 설계 방식, 제작 공정 및 측정 등을 포함하여 양극산화 알루미늄 패키지 기판의 특성과 성능을 분석하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제24권6호
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• pp.61-69
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• 2000

Indium-Tin Oxide (ITO) films were prepared on the commercial glass substrate by the Magnetron Sputtering method. The target was a 90wt.% $In_2O_3$-10wt.% $SnO_2$with 99.99% purity. The ITO films deposited by changing the partial pressure of oxygen gas ($O_2$/(Ar+$O_2$)) of 2, 3 and 5% as well as by changing the substrate temperature of $300^{\circ}C$ or $500^{\circ}C$. The influence of substrate pre-annealing and pre-cleaning on the quality of ITO film were examined, in which the substrate temperature was $500^{\circ}C$ and oxygen partial pressure was 3%. The characteristics of films were examined by the 4-point probe, Hall effect measurement system, SEM, AFM, Spectrophotometer, and X-ray diffraction. The optimum ITO films have been obtained when the substrate temperature is $500^{\circ}C$ and oxygen partial pressure is 3%. At optimum condition, the film showed transmittance of 81%, sheet resistivity of $226\Omegatextrm{cm}^2$, resistivity($\rho$) of $5.4\times10^{-3}\Omega$cm, carrier concentration of $1.0\times10^{19}cm^{-3}$, and carrier mobility of $150textrm{cm}^2$Vsec. From XRD spectrum, c(222) plane was dominant in the case of substrate temperature at $300^{\circ}C$, without regarding to oxygen partial pressure. However, in the case of substrate temperature at $500^{\circ}C$, c(400) plane was grown together with c(222) plane, only for oxygen partial pressure of 2 and 3%. In both case of chemical and ultrasonic cleaning without pre-annealing the substrate, it showed much almost same sheet resistivity, resistivity($\rho$), transmittance, carrier concentration, and carrier mobility. In case of $500^{\circ}C$/60min pre-annealing before ITO film deposited, both transimittance and carrier mobility are better than no pre-annealing, because pre-annealing is supposed to remove alkari ions diffusion from substrate. ITO film deposited on the Corning 0080 sybstrate showed a little bit better sheet resistivity, resistivity($\rho$), transimittance, carrier concentration than the film deposited on commercial glass. But no differences between Corning substrate and pre-annealed commercial glass substrate are found.

• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.327-331
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• 2008

An in-line wet etch/cleaning system was established for the research and development in wet etch process as a formation of electrode such as metal or transparent conductive oxide layer. A reverse moving system was equipped in the in-line wet etch/cleaning system for the alternating motion of glass substrate in a wet etch bath of the system. Therefore, it was possible for the glass substrate to be moved back and forth and it was possible to reduce the size of the system by using the reversing moving system. For the effect of the alternating motion of substrate on the etch rate in the in-line wet etch bath, indium tin oxide(ITO) patterns were obtained through wet etch process in the in-line system in which the substrate was moved back and forth. From the CD(critical dimension) skews resulted from the ADI CD and ACI CD of the ITO patterns, it was concluded that the alternating motion of glass substrate are possible to be applied to the mass production of wet etch process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.93-93
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• 2011

The Indium Zinc Tin Oxide (IZTO) and Indium Tin Oxide (ITO) thin films are grown on PI substrate at different substrate temperature by pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt.%, ZnO 15 wt.%, SnO2 15 wt.%) and ITO (In2O3 90wt.%, SnO2 10wt.%). The structural, electrical, and optical properties are investigated. The IZTO thin films deposited at low temperature showed relatively low electrical resistivity compared to ITO thin films deposited at low temperature. As a result, we could prepare the IZTO thin films with the resistivity as low as $5.6{\times}10^{-4}({\Omega}{\cdot}m)$. Both of the films deposited on PI substrate showed an average transmittance over 80% in visible range (400.800nm). Overall, IZTO thin film is a promising candidate as an alternative TCO material to ITO in flexible and OLED devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 기술교육전문연구회
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• pp.58-61
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• 2003

ITO (indium tin oxide) thin films on PET (polyethylene terephthalate) substrate have been deposited by a dc reactive magnetron sputtering without heat treatments such as substrate heater and post heat treatment. Each sputtering parameter during the sputtering deposition is an important factor for the high quality of ITO thin films deposited on polymeric substrate. Particularly, the material, electrical and optical properties of as-deposited ITO oxide films are dominated by the ratio of oxygen partial pressure. As the experimental results, the excellent ITO films are prepared on PET substrate at the operating conditions as follows: operating pressure of 5 mTorr,target-substrate distance of 45 mm, dc power of 20-30 W, and oxygen gas ratio of 10 %. The optical transmittance is above 80 % at 550 nm, and the sheet resistance and resistivity of films are $24\;{\Omega}$/square and $1.5{\times}10^{-3}\;cm$, respectively.

• 전기학회논문지
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• 제67권6호
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• pp.799-803
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• 2018

We demonstrated memory thin-film transistors (MTFTs) with organic ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethylene) and an amorphous oxide semiconducting indium gallium zinc oxide channel on the elastomeric substrate. The dielectric constant for the P(VDF-TrFE) thin film prepared on the elastomeric substrate was calculated to be 10 at a high frequency of 1 MHz. The voltage-dependent capacitance variations showed typical butterfly-shaped hysteresis behaviors owing to the polarization reversal in the film. The carrier mobility and memory on/off ratio of the MTFTs showed $15cm^2V^{-1}s^{-1}$ and $10^6$, respectively. This result indicates that the P(VDF-TrFE) film prepared on the elastomeric substrate exhibits ferroelectric natures. The fabricated MTFTs exhibited sufficiently encouraging device characteristics even on the elastomeric substrate to realize mechanically stretchable nonvolatile memory devices.