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Effects of Film Thickness and Annealing Temperature on the Specific Contact Resistivity and the Transmittance of the IZO Layers Grown on p-GaN by Roll-to-Roll Sputtering (p-GaN 위에 Roll-to-Roll sputter로 성장된 IZO의 접촉 비저항 및 투과도에 대한 박막 두께와 열처리 온도의 영향)

  • Kim, Jun Young;Kim, Jae-Kwan;Han, Seung-Cheol;Kim, Han Ki;Lee, Ji-Myon
    • Korean Journal of Metals and Materials
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    • v.48 no.6
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    • pp.565-569
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    • 2010
  • We report on the characteristics of indium-oxide-doped ZnO (IZO) ohmic contact to p-GaN. The IZO ohmic contact layer was deposited on p-GaN by a Roll-to-Roll (RTR) sputter method. IZO contact film with a thickness of 360, 230 and 100 nm yielded an ohmic contact resistance of 4.70×104, 5.95×102, 4.85×101Ωcm2 on p-GaN when annealed at 600C for 1 min under a nitrogen ambient, respectively. While the transmittance of IZO film with a thickness of 360 nm slightly increased in the wavelength range of 380-800 nm after annealing, the transmittance rapidly increased up to 80% after annealing at 600C in the wavelength range of 380~430 nm because the crystallization of IZO film and created Ga vacancies near the p-GaN surface region were affected by the annealing. These results indicate that ohmic contact resistance and transmittance of the IZO films improved.

Characterization of arsenic doped p-type ZnO thin film (As 토핑된 p형 ZnO 박막의 특성 분석)

  • Kim, Dong-Lim;Kim, Gun-Hee;Chang, Hyun-Woo;Ahn, Byung-Du;Lee, Sang-Yeol
    • Proceedings of the KIEE Conference
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    • 2006.10a
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    • pp.53-54
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    • 2006
  • Arsenic doped p-type ZnO thin films have been realized on intrinsic (100) GaAs substrate by RF magnetron sputtering and thermal annealing treatment. p-Type ZnO exhibits the hole concentration of 9.684×1019cm3, resistivity of 2.54×103Ωcm, and mobility of 25.37cm2/Vs. Photoluminescence (PL) spectra of As doped p-type ZnO thin films reveal neutral acceptor bound exciton (A0X) of 3.3437 eV and a transition between free electrons and acceptor levels (FA) of 3.2924 eV. Calculated acceptor binding energy (EA) is about 0.1455 eV. Thermal activation and doping mechanism of this film have been suggested by using X-ray photoelectron spectroscopy (XPS). p-Type formation mechanism of As doped ZnO thin film is more related to the complex model, namely, AsZn2VZn, in which the As substitutes on the Zn site, rather than simple model, Aso, in which the As substitutes on the O site. ZnO-based p-n junction was fabricated by the deposition of an undoped n-type ZnO layer on an As doped p-type ZnO layer.

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Combinatorial Approach for Systematic Studies in the Development of Transparent Electrodes

  • Kim, Tae-Won;Kim, Sung-Dae;Heo, Gi-Seok;Lee, Jong-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.28-28
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    • 2008
  • We have demonstrated the combinatorial synthesis of a variety of transparent conducting oxides using a combinatorial sputter system. The effects of a wide range of Nb or Zn doping rate on the optical and electrical properties of Indium-tin oxides (ITO) films were investigated. The Nb or Zn doped ITO films were fabricated on glass substrates, using combinatorial sputtering system which yields a linear composition spread of Nb or Zn concentration in ITO films in a controlled manner by co-sputtering two targets of ITO and Nb2O5 or ITO and ZnO. We have examined the work-function, resistivity, and optical properties of the Nb or Zn-doped ITO films. Furthermore, the effects of Hz plasma treatment on the physical properties of Ga or Zn doped ITO films synthesized by combinatorial sputter system were investigated.

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Synthesis of p-Type ZnO Thin Film Prepared by As Diffusion Method and Fabrication of ZnO p-n Homojunction

  • Kim, Deok Kyu
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.6
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    • pp.372-375
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    • 2017
  • ZnO thin films were deposited by RF magnetron sputtering and then diffused by using an As source in the ampouletube. Also, the ZnO p-n homojunction was made by using As-doped ZnO thin films, and its properties were analyzed. After the As doping, the surface roughness increased, the crystal quality deteriorated, and the full width at half maximum was increased. The As-doped ZnO thin films showed typical p-type properties, and their resistivity was as low as 2.19×103Ωcm, probably because of the in-diffusion from an external As source and out-diffusion from the GaAs substrate. Also, the ZnO p-n junction displayed the typical rectification properties of a p-n junction. Therefore, the As diffusion method is effective for obtaining ZnO films with p-type properties.

Luminescent Properties of Mn2+ co-doped Ca8Mg1(SiO4)4Cl2:Eu2+ phosphor and Application in white LEDs

  • Park, Seung-Hyok;Park, Jung-Kyu;Kim, Chang-Hee;Chang, Hyun-Ju;Jang, Ho-Gyeom
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1529-1530
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    • 2007
  • The manganese co-doped Ca8Mg1(SiO4)4Cl2:Eu2+,Mn2+ phosphor was synthesized by solid-state reaction and its photoluminescence characteristics were investigated. The synthesized phosphor show two emission spetrums: green band of 512nm and yellow band of 550nm. White light-emitting diodes (LEDs) were fabricated through combination of a 405nm-emitting InGaN chip and a synthesis phosphor in a single package. Under 20mA current, its CIE chromaticity coordinates are x=0.40 and y=0.45 and a color temperature of 4053K.

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Property of gallium doped Zinc Oxide thin film deposited with various substrate temperatures using D.C. magnetron sputtering

  • Kim, Se-Hyun;Moon, Yeon-Geon;Moon, Dae-Yong;Park, Jong-Wan;Jeong, Chang-Ho
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1351-1354
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    • 2006
  • In this paper, we study the effect of substrate temperature on property of Ga doped ZnO (GZO) thin film for transparent conductive oxide (TCO).GZO thin films have been deposited on corning glass 1737 by D.C. magnetron sputtering. We investigated the structural and electrical properties of GZO films using the X-Ray Diffractometer(XRD), Field Emission Scanning Electron Microscopy(FESEM) and 4-points probe .

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Study of High-efficiency and Long-lived Blue - Green Light Emitting Diodes Using ZnSSe:Te System Grown by MBE (ZnSSe:Te계 청 -녹색 발광다이오드의 고효율화 및 장수명화에 관한 연구)

  • 이홍찬;이상태;이성근;김윤식
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2002.05a
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    • pp.167-171
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    • 2002
  • We have investigated the optical properties of Te-doped ZnSSe:Te epitaxial layers grown on (100) GaAs substrates by molecular beam epitaxy. The Te-doped ternary specimen shows strong blue or green emission (at 300k) which is assigned to Te1 or Ten( n2) cluster bound exciton. Bright green and blue light-emitting diodes (LEDs) have been developed using ZnSSe:Te system as an active layer. The green LEDs exhibit a fairly long device lifetime (>2000 h) when operated at 3 A/cm2 under CW condition at room temperature. It is confirmed that the Te-doping induced "crystal-hardening effect" plays a significant role in both efficient and strong suppression of the optical device degradation.gradation.

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Characterization of conducting aluminium doped zinc oxide (ZnO:Al) thin films deposited on polymer substrates (폴리머 기판위에 증착된 ZnO:Al 전도막의 특성연구)

  • Koo, Hong-Mo;Kim, Se-Hyun;Park, Jong-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.535-538
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    • 2004
  • Zinc Oxide (ZnO) films have attracted considerable attention for transparent conducting films, because of their high conductivity, good optical transmittance from UV to near IR as well as a low-cost fabrication. To increase the conductivity of ZnO, doping of group III elements (Al, Ga, In and B) has been carried out. Transparent conducting films have been applied for optoelectric devices, the development of the transparent conducting thin films on flexible light-weight substrates are required. In this research, the transparent conducting ZnO thin films doped with Aluminum (Al) on polymer substrates were deposited by the RF magnetron suputtering method, and the structural, optical and electrical properties were investigated.

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Pulsed Laser Deposition을 이용하여 GZO/Glass 기판상에 성장시킨 염료감응형 태양전지용 TiO2 Blocking Layer의 특성 연구

  • Yeo, In-Hyeong;Kim, Ji-Hong;No, Ji-Hyeong;Kim, Jae-Won;Do, Gang-Min;Sin, Ju-Hong;Jo, Seul-Gi;Park, Jae-Ho;Mun, Byeong-Mu
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.259-259
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    • 2011
  • 염료감응형 태양전지(Dye-Sensitized Solar Cells:DSSC)는 환경 친화적이며, 저가의 공정에 대한 가능성으로 기존의 고가의 결정질 실리콘 태양전지의 경제적인 대안으로 각광을 받고 있다. 최근 염료감응형 태양전지는 투명 전도성 산화막(Transparent Conducting Oxide : TCO)으로 사용되는 Fluorine Tin Oxide (FTO)가 증착된 유리기판 위에 주로 제작된다. FTO는 낮은 비저항과 가시광선 영역에서 높은 투과도를 가지는 우수한 전기-광학적 특성을 갖지만, 비교적 공정이 까다로운 Chemical Vapor Deposition (CVD)법으로 제조하며, 전체 공정비용의 60%를 차지하는 높은 생산단가로 인해 현재 FTO를 대체할 재료개발 연구가 활발히 진행되고 있다. 그 중 ZnO (Zinc Oxide)는 우수한 전기-광학적 특성과 비교적 저렴한 가격으로 새로운 TCO로써 주목받고 있다. ZnO는 넓은 energy band gap (3.4 [eV])의 육방정계 울자이트(hexagonal wurtzite) 결정 구조를 가지는II-VI족 n형 반도체 물질이며, III족 금속원소인 Al, Ga 및 In 등의 불순물을 첨가하면 TCO로서 우수한 전기-광학적 특성과 안정성을 나타낸다. 이들 물질중 Zn2+ (0.060 nm)의 이온반경과 유사한 Ga2+0.062 nm) 이온이 ZnO의 격자반경을 최소화 시킬 수 있다는 장점으로 최근 주목 받고 있다. 하지만 Ga-doped ZnO (GZO)의 경우 DSC에 사용되는 루테늄 계열의 산성 염료 하에 장시간 두면 표면이 파괴되는 문제가 발생하며, TiO2 paste를 Printing 후 열처리하는 과정에서도 박막의 파괴가 발생할 수 있다. 이를 방지하기 위해 TiO2 Blocking Layer를 GZO 투명전극 위에 증착하였다. 또한, TiO2 Blocking Layer를 적용한 GZO 박막을 전면전극으로 이용하여 DSC를 제작하여 효율을 확인하였다. 2wt%의 Ga2O3가 도핑된 ZnO 박막은 20mTorr 400C에서 Pulsed Laser Deposition (PLD)에 의해 성장되었고, TiO2박막은 Ti 금속을 타겟으로 이용하여 30mTorr 400C에서 증착되었다. Scanning electron microscopy (FE-SEM)을 이용한 박막 분석 결과 TiO2가 증착된 GZO 박막의 경우 표면 파괴가 일어나지 않았다. Solar Simulator을 이용하여 I-V특성 측정결과 상용 FTO를 사용한 DSC 수준의 효율을 나타내었다. 이에 따라 Pulsed Laser Deposition을 이용해 제작된 GZO 기판은 TiO2 Blocking Layer를 이용하여 표면 파괴를 방지할 수 있었으며, 이는 향후 염료감응형 태양전지의 투명전극에 적용 가능 할 것으로 판단된다.

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High Voltage β-Ga2O3 Power Metal-Oxide-Semiconductor Field-Effect Transistors (고전압 β-산화갈륨(β-Ga2O3) 전력 MOSFETs)

  • Mun, Jae-Kyoung;Cho, Kyujun;Chang, Woojin;Lee, Hyungseok;Bae, Sungbum;Kim, Jeongjin;Sung, Hokun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.3
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    • pp.201-206
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    • 2019
  • This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide (Ga2O3) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating βGa2O3 (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of 10×15mm2. Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length (Lg) of 2μm and a gate-drain spacing (Lgd) of 5μm. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for $V_{gs}<-6V$, and the three-terminal off-state breakdown voltage was over 482 V in a Lgd=5μm device measured in Fluorinert ambient at Vgs=10V. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately 5.3×105. These device characteristics indicate the promising potential of Ga2O3-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.