• Title/Summary/Keyword: Multi-layer materials

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Multi-step growth of a-plane GaN epitaxial layer on r-plane sapphire substrate by HVPE method (HVPE를 이용하여 r-plane 사파이어 위에 multi-step으로 성장시킨 a-plane GaN 에피층의 특성 연구)

  • Lee, Won-Jun;Park, Mi-Seon;Jang, Yeon-Suk;Lee, Won-Jae;Ha, Ju-Hyung;Choi, Young-Jun;Lee, Hae-Yong;Kim, Hong-Seung
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.3
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    • pp.89-94
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    • 2016
  • In this study, the crystalline property of a-plane GaN epitaxial layer grown on r-plane sapphire by a HVPE method has been investigated according to the V/III ratio and the growth time of multi-step growth. Furthermore, these results were compared with the previous result obtained from the single-step growth of a-plane GaN on r-plane sapphire substrate. In the multi-step growth for a-plane GaN epitaxial layer on r-plane sapphire, the FWHM values of rocking curve in GaN epitaxial layer were decreased as the HCl source flow rate and the growth time were increased. The void formed in epitaxial layer was continuously decreased as the growth time in first step and second step using a higher HCl flow rate was increased. As a result, the GaN layer obtained with the longest growth time on the first step and second step exhibited the lowest FWHM values of 584 arcsec and the smallest dependence of azimuth angle.

The oxidation of silicon nitride layer (실리콘 질화막의 산화)

  • 정양희;이영선;박영걸
    • Electrical & Electronic Materials
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    • v.7 no.3
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    • pp.231-235
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    • 1994
  • The multi-dielectric layer $SiO_2$/$Si_3{N_4}$/$SiO_2$ (ONO) is used to improve charge retention and to scale down the memory device. The nitride layer of MNOS device is oxidize to form ONO system. During the oxidation of the nitride layer, the change of thickness of nitride layer and generation of interface state between nitride layer and top oxide layer occur. In this paper, effects of oxidation of the nitride layer is studied. The decreases of the nitride layer due to oxidation and trapping characteristics of interface state of multi layer dielectric film are investigated through the C-V measurement and F-N tunneling injection experiment using SONOS capacitor structure. Based on the experimental results, carrier trapping model for maximum flatband voltage shift of multi layer dielectric film is proposed and compared with experimental data. As a results of curve fitting, interface trap density between the top oxide and layer is determined as being $5{\times}10^11$~$2{\times}10^12$[$eV^1$$cm^2$].

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Structural and Electrical Properties High Resistance of TiNxOy/TiNx Multi-layer Thin Film Resistors (TiNxOy/TiNx 다층 박막을 이용한 고저항 박막 저항체의 구조 및 전기적 특성평가)

  • Park, Kyoung-Woo;Hur, Sung-Gi;Nguyen, Duy Cuong;Ahn, Jun-Ku;Yoon, Soon-Gil
    • Korean Journal of Metals and Materials
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    • v.47 no.9
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    • pp.591-596
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    • 2009
  • $TiN_xO_y/TiN_x$ multi-layer thin films with a high resistance(${\sim}k{\Omega}$) were deposited on $SiO_2/Si$ substrates at room temperature by sputtering. The $TiN_x$ thin films show island and smooth surface morphology in samples prepared by ${\alpha}$ and RF magnetron sputtering, respectively. $TiN_xO_y/TiN_x$ multi-layer in has been developed to control temperature coefficient of resistance(TCR) by the incorporation of $TiN_x$ layer(positive TCR) inserted into $TiN_xO_y$ layers(negative TCR). Electrical and structural properties of sputtered $TiN_xO_y/TiN_x$ multi-layer films were investigated as a function of annealing temperature. In order to achieve a stable high resistivity, multi-layer films were annealed at various temperatures in oxygen ambient. Samples annealed at $700^{\circ}C$ for 1 min exhibited good TCR value of approximately $-54 ppm/^{\circ}C$ and a stable high resistivity around $20k{\Omega}/sq$. with good reversibility.

Effect of Fines Distribution on Press Dewatering and Physical Properties of Multi-ply Sheet

  • Lee, Hak-Lae;Youn, Hye-Jung;Kang, Tae-Young;Choi, Ik-Sun
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.40 no.5
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    • pp.36-41
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    • 2008
  • Multi-ply sheet forming has many advantages including the possibility of using wide range of materials in a given structure, lowering production cost, making higher grammage products and so on. But, incorrect structure of sheet makes flow resistance higher so that it shows poor dewatering in press section. One of major factors that affect sheet structure and dewatering property is fines content in each layer. We, therefore, examined the press dewatering of multi-ply sheet that has the different fines content in each layer and the effect of fines distribution on physical properties of sheet to find a technology for optimum utilization of raw materials. In case of two layered sheet, the sheet which was composed of layers with the different flow resistance showed higher dewatering rate than one which has the same flow resistance. And the more difference in fines content for layers existed, the more dewatering occurred. For three layered sheets, dewatering is mainly dependent on fines content of bottom layer. Strength properties were affected by dewatering degree and multi-ply sheet structure.

Effect of Si3N4 Buffer Layer on Transmittance of TiO2/Si3N4/Ag/Si3N4/TiO2 Multi Layered Structure (TiO2/Si3N4/Ag/Si3N4/TiO2 다층구조에서 Si3N4 버퍼층이 투과율에 미치는 영향)

  • Lee, Seo-Hee;Jang, Gun-Eik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.1
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    • pp.44-47
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    • 2012
  • The $TiO_2/Si_3N_4/Ag/Si_3N_4/TiO_2$ multi layered structure was designed for the possible application of transparent electrodes in PDP (Plasma Display Panel). Multi layered film was deposited on a glass substrate at room temperature by DC/RF magnetron sputtering system and EMP (Essential Macleod Program) was adopted to optimize the optical characteristics of film. During the deposition process, the Ag layer in $TiO_2/Ag/TiO_2$ became heavily oxidized and the filter characteristic was degraded easily. In thus study, Si3N4 layer was used as a diffusion buffer layer between $TiO_2$ and Ag. in order to prevent the oxidation of Ag layer in $TiO_2/Si_3N_4/Ag/Si_3N_4/TiO_2$ structure. It was confirmed that $Si_3N_4$ layer is one of candidate materials acting as diffusin barrier between $TiO_2/Ag/TiO_2$.

Evaluation of Corrosion and Surface Resistance of Ni-Px/C Multi Layer (Ni-Px/C 다층 도금층의 내식성과 표면 전기저항 평가)

  • Park, Je-Sik;Jung, Eun-Kyung;Lee, Churl-Kyoung
    • Journal of the Korean institute of surface engineering
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    • v.45 no.4
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    • pp.162-167
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    • 2012
  • Ni-P/C multi-layer was synthesized by electroless plating and paste coating for better corrosion and surface conductance as a metallic bipolar plate. The Ni-P layer could be synthesized with the range of 2.6~22.4 at.% P contents and it's surface morphology and corrosion resistance depend on content of P. Corrosion resistance of the Ni-P layer in sulfuric acid by electrochemical test is similar with pure Ni. Surface resistance of pure Ni after corrosion was increased about 8% compared to pure Ni. On the other hand, that of the Ni-P/C composite with 20% carbon content was increased only 1%.

Improved Efficiency of Polymer LEDs using Electron Transporting Layer

  • Kim, Jong-Lae;Kim, Jai-Kyeong;Cho, Hyun-Nam;Kim, Dong-Young;Hong, Sung-Il;Kim, Chung-Yup
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.125-126
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    • 2000
  • We report the use of fluorene based copolymers containing quinoline(POF66, PIF66) and pyridine(PFPV) units as electron transporting polymers for multi-layered LEDs. Double-layer device structure combining PIF66 as electron-transporting layer with the emissive MEHPPV showed a maximum quantum efficiency of 0.03%, which is 30 fold increased compared with ITO/MEHPPV/Al single-layer device. PFPV layer increased the quantum efficiency up to 0.1% in the device structure of ITO/(P-3:PVK)/PFPV/Al. The ETL with the electron deficient moiety improved the LED performance by the characteristics of electron transporting as well as hole blocking between emissive layer and metal cathode.

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Emission rates of VOCs/VVOCs from multi-layers and their impacts on indoor air quality of Apartments (마감공사후 경과시간에 따른 복합마감재의 VOCs/VVOCs 방출량과 실내농도에 관한 연구)

  • Yoon, Chang-Hyun;Kwon, Kyung-Woo;Park, Jun-Seok
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.295-300
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    • 2006
  • The purpose of this study is to evaluate the impacts of finishing materials' VVOCs and VOCs emission rates on indoor air quality of Apartment. VOCs emission rate of multi-layer finishing is predicted using the effective diffusion coefficient of each materials, and then the prediction is compared with Mock-up test and sample apartment house. From the results, the prediction of multi-layer finishing using the effective diffusion coefficient show good relation with the measured values.

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The Properties of RF Sputtered Zinc Tin Oxide Thin Film Transistors at Different Sputtering Pressure (스퍼터 증착된 Zinc Tin Oxide 박막 트랜지스터의 공정 압력에 따른 특성 연구)

  • Lee, Hong Woo;Yang, Bong Seob;Oh, Seungha;Kim, Yoon Jang;Kim, Hyeong Joon
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.1
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    • pp.43-49
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    • 2014
  • Zinc-tin oxides (ZTO) thin film transistors have been fabricated at different process pressure via re sputtering technique. TFT properties were improved by depositing channel layers at lower pressure. From the analysis of TFTs comprised of multi layer channel, deposited consecutively at different sputtering pressure, it was suggested that the electrical characteristics of TFTs were mainly affected by interfacial layer due to their high conductance, however, the stability under the NBIS condition was influenced by whole bulk layer due to low concentration of positive charges, which might be generated by the oxygen vacancy transition, from Vo0 to $Vo^{2+}$. Those improvements were attributed to increasing sputtered target atoms and decreasing harmful effects of oxygen molecules by adopting low sputtering pressure condition.

금속이 코팅된 PET필름의 수분침투 특성 평가

  • Choe, Yeong-Jun;Park, Gi-Jeong;Jo, Yeong-Rae
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.05a
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    • pp.36.1-36.1
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    • 2009
  • OLED(organic light emitting diode)는 차세대 평판 디스플레이로 전자종이, 입는 디스플레이 등 flexible한 디스플레이로도 주목받고 있다. 하지만, OLED의 가장 큰 단점 중의 하나가 수분과 산소에 매우 민감하다는 것으로 이것은 OLED의 lifetime과 연결된다. 따라서 이에 대한 mechanism의 확립이 필요하다. 따라서 본 연구에서는, flexible한 OLED에 적용되는 금속 코팅막의 적층구조 및 기판의 노출온도에 따른 금속 코팅막의 수분침투 특성에 대해 MOCON의 weight gain test (WGT)를 통해 barrier layer에 대해 평가하고 이에 대한 mechanism을 확립하는데 그 목적이 있다. 금속 코팅막은 OLED의 cathode와 anode 재료로 많이 사용되는 Al과 ITO를 sputter장비를 이용해 single layer와 multi-layer의 두 가지 구조로 PET기판에 증착하였다. 또한, 노출온도에 따른 특성을 알아보고자 bare PET / ITO coated PET(single layer $50{\mu}m$) / Al coated PET(single layer $200{\mu}m$)의 세 가지 시편을 제작하였다. 이 시편을 각각 $25^{\circ}C$, $37.8^{\circ}C$, $50^{\circ}C$의 온도에서 test를 진행하였고 이 과정을 100%RH, 70%RH, 40%RH조건의 수분조건에서 진행하여 각각의 수분조건에서 각각의 온도에 따른 금속 코팅막의 수분침투 특성에 대한 mechanism을 확립하였다. 적층구조에 따른 수분침투 특성 평가 결과 multi-layer가 single layer보다 더 우수한 수분침투의 barrier 특성을 나타냈었다. 그리고 각 온도에 따른 test결과 온도가 증가할수록 barrier의 특성이 나빠짐이 보였다.

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