• Title/Summary/Keyword: ZnO thin films

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Photoluminescence Studies of ZnO Thin Films on Porous Silicon Grown by Plasma-Assisted Molecular Beam Epitaxy

  • Kim, Min-Su;Nam, Gi-Woong;Kim, So-A-Ram;Lee, Dong-Yul;Kim, Jin-Soo;Kim, Jong-Su;Son, Jeong-Sik;Leem, Jae-Young
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.310-310
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    • 2012
  • ZnO thin films were grown on porous silicon (PS) by plasma-assisted molecular beam epitaxy (PA-MBE). The optical properties of the ZnO thin films grown on PS were studied using room-temperature, low-temperature, and temperature-dependent photoluminescence (PL). The full width at half maximum (FWHM) of the near-band-edge emission (NBE) from the ZnO thin films was 98 meV, which was much smaller than that of ZnO thin films grown on a Si substrate. This value was even smaller than that of ZnO thin films grown on a sapphire substrate. The Huang-Rhys factor S associated with the free exciton (FX) emission from the ZnO thin films was found to be 0.124. The Eg(0) value obtained from the fitting was 3.37 eV, with ${\alpha}=3.3{\times}10^{-2}eV/K$ and ${\beta}=8.6{\times}10^3K$. The low- and high-temperature activation energies were 9 and 28 meV, respectively. The exciton radiative lifetime of the ZnO thin films showed a non-linear behavior, which was established using a quadratic equation.

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Improvement of the characteristics of ZnO thin films using ZnO buffer layer (ZnO 저온 성장 버퍼에 의한 ZnO 박막의 특성 향상)

  • Pang, Seong-Sik;Kang, Jeong-Seok;Kang, Hong-Seong;Shim, Eun-Sub;Lee, Sang-Yeol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.65-68
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    • 2002
  • The effect of low-temperature ZnO buffer layer has been investigated for the optical properties of ZnO thin films. ZnO buffers and thin films have been deposited using the pulsed laser deposition technique. ZnO buffer layers were grown at $200^{\circ}C$ with various thickness of 0 to 60 nm, followed by raising the substrate temperature to $400^{\circ}C$ to grow $2{\mu}m$ ZnO thin films. The buffer layers could relax stresses induced by the lattice mismatch and different thermal expansion coefficients between ZnO thin films and sapphire substrate. In order to identify the optical properties of ZnO thin films, PL measurement was used. From the results of PL measurement, all the fabricated ZnO thin films with buffer layers have shown intensive UV emission with a narrow linewidth. ZnO thin films with buffer layer of 20 nm have shown the strongest UV emission. It was found that the use of ZnO buffer layer plays an important role to improve the intensive UV emission of the ZnO thin films.

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Characterization and deposition of ZnO thin films by Reactive Magnetron Sputtering using Inductively-Coupled Plasma (ICP) (유도결합형 플라즈마를 사용한 반응성 마그네트론 스퍼터링에 의한 ZnO 박막 증착 및 특성분석)

  • Kim, Dong-Sun
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.2
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    • pp.83-89
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    • 2011
  • In this study, we investigated the effects of shutter control by Reactive Magnetron Sputtering using Inductively-Coupled Plasma(ICP) for obtaining ZnO thin films with high purity. The surface morphologies and structure of deposited ZnO thin films were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray Diffractometer (XRD). Also, optical and chemical properties of ZnO thin films were analyzed by Spectroscopic Ellipsometer (SE) and X-ray Photoelectron spectroscopy (XPS). As a result, it observed that ZnO thin films grown at reactive sputtering using shutter control and ICP were higher density, lower surface roughness, better crystallinity than other conventional sputtering deposition methods. For obtaining better quality deposition ZnO thin films, we will investigate the effects of substrate temperature and RF power on shutter control by a reactive magnetron sputtering using inductively-coupled plasma.

Growth of ZnO Thin films Depending on the Substrates by RF Sputtering and Analysis of Their Microstructures (기판의 결정구조에 따른 RF 스퍼터링 ZnO 박막의 성장과 미세구조 분석)

  • Yoo In-Sung;So Soon-Jin;Park Choon-Bae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.5
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    • pp.461-466
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    • 2006
  • To investigate the ZnO thin films which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF sputtering system. At sputtering process of ZnO thin films, substrate temperature, work pressure respectively is $100^{\circ}C$ and 15 mTorr, and the purity of target is ZnO 5 N. The ZnO thin films were in-situ annealed at $600^{\circ}C$ in $O_2$ atmosphere. The thickness of ZnO thin films has implemented about $1.6{\mu}m$ at SEM analysis after in-situ annealing process. We have investigated the crystal structure of substrates, and so structural properties of ZnO thin films has estimate by using XRD, FWHM, FE-SEM and AFM. XRD and FE-SEM showed that ZnO thin films grown on substrates had a c-axis preferential orientation in the [0001] crystal direction. XPS spectra showed that ZnO thin film was showed a peak positions corresponding to the O1s and the Zn2p. As form above XPS, we showed that the atom ratio of Zn:O related 1:1.1504 on ZnO thin film, so we could obtained useful information for p-type ZnO thin film.

The Microstructures and Electrical Properties of ZnO/Sapphire Thin Films Doped by P and As based on Ampouele-tube Method (Ampoule-tube 법으로 P와 As을 도핑한 ZnO/Sapphire 박막의 미세구조와 전기적 특성)

  • Yoo, In-Sung;Jin, Eun-Mi;So, Byung-Moon;Park, Choon-Bae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.120-121
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    • 2006
  • To investigate the ZnO thin films which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF magnetron sputtering system. Al sputtering process of ZnO thin films substrate temperature, work pressure respectively is $100^{\circ}C$ and 15 mTorr, and the purity of target is ZnO 5N. The ZnO thin films were in-situ annealed at $600^{\circ}C$, $800^{\circ}C$ in $O_2$ atmosphere. Phosphorus (P) and arsenic (As) were diffused into ZnO thin films sputtered by RF magnetron sputtering system in ampoule tube which was below $5{\times}10^{-7}$ Torr. The dopant sources of phosphorus and arsenic were $Zn_3P_2$ and $ZnAS_2$. Those diffusion was perform at $650^{\circ}C$ during 3hr. We confirmed that p-type properties of ZnO thin films were concerned with dopant sources rather than diffusion temperature.

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Influence of Oxygen Partial Pressure on ZnO Thin Films for Thin Film Transistors

  • Kim, Jae-Won;Kim, Ji-Hong;Roh, Ji-Hyoung;Lee, Kyung-Joo;Moon, Sung-Joon;Do, Kang-Min;Park, Jae-Ho;Jo, Seul-Ki;Shin, Ju-Hong;Yer, In-Hyung;Koo, Sang-Mo;Moon, Byung-Moo
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.106-106
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    • 2011
  • Recently, zinc oxide (ZnO) thin films have attracted great attention as a promising candidate for various electronic applications such as transparent electrodes, thin film transistors, and optoelectronic devices. ZnO thin films have a wide band gap energy of 3.37 eV and transparency in visible region. Moreover, ZnO thin films can be deposited in a poly-crystalline form even at room temperature, extending the choice of substrates including even plastics. Therefore, it is possible to realize thin film transistors by using ZnO thin films as the active channel layer. In this work, we investigated influence of oxygen partial pressure on ZnO thin films and fabricated ZnO-based thin film transistors. ZnO thin films were deposited on glass substrates by using a pulsed laser deposition technique in various oxygen partial pressures from 20 to 100 mTorr at room temperature. X-ray diffraction (XRD), transmission line method (TLM), and UV-Vis spectroscopy were employed to study the structural, electrical, and optical properties of the ZnO thin films. As a result, 80 mTorr was optimal condition for active layer of thin film transistors, since the active layer of thin film transistors needs high resistivity to achieve low off-current and high on-off ratio. The fabricated ZnO-based thin film transistors operated in the enhancement mode with high field effect mobility and low threshold voltage.

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Effects of post-annealing treatment of ZnO Thin Films by Pulsed Laser Deposition (PLD를 이용한 ZnO 박막의 후열처리에 관한 연구)

  • Kim, Jae-Hong;Lee, Cheon
    • Proceedings of the KIEE Conference
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    • pp.1627-1630
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    • 2004
  • ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266nm. Before post-annealing treatment in the oxygen ambient, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $300{\sim}450^{\circ}C$ and flow rate of 100${\sim}$700 seem. In order to investigate the effect of post-annealing treatment of ZnO thin films, films have been annealed at various temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by X-ray diffraction(XRD) and the optical properties of the ZnO were characterized by photoluminescence(PL).

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Microstructure of ZnO Thin Films Deposited by PECVD using Diethylzine (Diethylzinc를 사용하여 PECVD로 증착한 ZnO 박막의 미세 구조 분석)

  • 김영진;김형준
    • Korean Journal of Crystallography
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    • v.4 no.2
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    • pp.92-99
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    • 1993
  • ZnO thin films were depositsd by Plasma enhanced CVD (PUW) using Diethylzinc and N2O gas, and micro-structue of ZnO thin films were investigated ZnO thin films composed of micro-crystallites was deposited at the substrate of loot. However, highly c-axis oriented ZnO thin films were deposited on the glass substrates above 200℃. TEM analysis revealed that an epitaxial (002) ZnO thin film was deposited on c-plane sapphire substrate at the substrate temperature of 350℃, and More patterns showing partial dislocation were observed at the grain boundary.

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Investigation on the Micro-photoluminescence of ZnO Thin Films Grown by Pulsed Laser Deposition (펄스 레이져 증착법으로 성장한 ZnO 박막의 마이크로 PL 특성 분석)

  • Lee, Deuk-Hee;Leem, Jae-Hyeon;Kim, Sang-Sig;Lee, Sang-Yeol
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.9
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    • pp.756-759
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    • 2009
  • We described the growth of undoped ZnO thin films and their optical properties changing with a various growth temperature. The undoped ZnO thin films were grown on $c-Al_2O_3$ substrates using pulsed laser deposition (PLD) at room temperature, 200, 400, and $600^{\circ}C$, respectively. Field emission microscopy (FE-SEM) measurements showed that the grain size of undoped ZnO thin films are increasing as a increase of growth temperature. In addition, we were investigated that the structural and optical properties of undoped ZnO thin films by x-ray diffraction (XRD) and photoluminescence (PL) studied. Also, we could confirmed that the exciton luminescence was strongly related to charge trap by grain boundary of the samples using micro-PL measurement.

Effects of Post-Annealing Treatment of ZnO Thin Films by Pulsed Laser (PLD를 이용한 ZnO 박막의 후열처리에 관한 연구)

  • Lee Cheon;Kim Jae-Hong
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.3
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    • pp.103-108
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    • 2005
  • ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266nm. Before post-annealing treatment in the oxygen ambient, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $300\~450^{\circ}C$ and oxygen gas flow rate of $100\~700\;sccm$. In order to investigate the effect of post-annealing treatment of ZnO thin films, films have been annealed at various temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and the optical properties of the ZnO were characterized by photoluminescence(PL).