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A Study on the Dependency of Pulsed-DC Sputtered Aluminum-doped Zinc Oxide Thin Films on the Reverse Pulse Time (Pulsed-DC 스퍼터링에서 Reverse Pulse Time에 따른 AZO 박막의 특성 변화에 관한 연구)

  • Ryu, Hyungseok;Zhao, Zhenqian;Kwon, Sang Jik;Cho, Eou Sik
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.4
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    • pp.32-36
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    • 2018
  • For various oxygen($O_2$) to argon(Ar) gas ratio, aluminum-doped zinc oxide(AZO) films were deposited for 3 min at different duty ratio by changing reverse pulse times. As the duty ratio increased, the thickness of the AZO film decreased and the sheet resistance increased. It can be concluded that When sputtering AZO Thin film, oxygen interfered with sputtering. When the reverse time was increased, the thickness of AZO was proportional to the real sputtering time and decreased. From the optical transmittance and sheet resistance, it was possible to obtain a higher figure of merits of AZO at a lower reverse pulse time. Even at the short reversed pulse time, it can be concluded that the accumulated charges on the AZO target are completely cleared. At a lower reverse pulse time, pulsed-DC sputtering of AZO is expected to be used instead of DC sputtering in the deposition of transparent conductive oxide(TCO) films without any degradation in thickness and structural/electrical characteristics.

Bandgap Voltage Reference Circuit Design Technology Suitable for Driving Large OLED Display Panel (대형 OLED 디스플레이 패널 구동에 적합한 밴드갭 레퍼런스 회로 설계 및 결과)

  • Moon, Jong Il;Cho, Sang Jun;Cho, Eou Sik;Nam, Chul;Kwon, Sang Jik
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.2
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    • pp.53-56
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    • 2018
  • In this paper, a CMOS bandgap voltage reference that is not sensitive to changes in the external environment is presented. Large OLED display panels need high supply voltage. MOSFET devices with high voltage are sensitive to the output voltage due to the channel length modulation effect. The self-cascode circuit was applied to the bandgap reference circuit. Simulation results show that the maximum output voltage change of the basic circuit is 77mV when the supply voltage is changed from 10.5V to 13.5V, but the proposed circuit change is improved to 0.0422mV. The improved circuit has a low temperature coefficient of $9.1ppm/^{\circ}C$ when changing the temperature from $-40^{\circ}C$ to $140^{\circ}C$. Therefore, the proposed circuit can be used as a reference voltage source for circuits that require a high supply voltage.

Study on the Atomic Layer Deposition System and Process of the MgO Thin Layer for the Thin Film Encapsulation of OLED (OLED의 Thin Film Encapsulation을 위한 MgO 박막의 원자층 증착 장치 및 공정에 관한 연구)

  • Cho, Eou Sik;Kwon, Sang Jik
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.22-26
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    • 2021
  • Thin-film encapsulation (TFE) technology is most effective in preventing water vapor and oxygen permeation in the organic light emitting diodes (OLED). Of those, a laminated structure of Al2O3 and MgO were applied to provide efficient barrier performance for increasing the stability of devices in air. Atomic layer deposition (ALD) method is known as the most promising technology for making the laminated Al2O3/MgO and is used to realize a thin film encapsulation technology in organic light-emitting diodes. Atomic layer deposited inorganic films have superior barrier performance and have advantages of excellent uniformity over large scales at relatively low deposition temperatures. In this study, the control system of the MgCP2 precursor for the atomic layer deposition of MgO was established in order to deposit the MgO layer stably by the injection time of second level and the stable heating temperature. The deposition rate was obtained stably to be from 4 to 10 Å/cycle using the injection pulse times ranging from 3 to 12 sec and a substrate temperature ranging from 80 to 150 ℃.

Consumer Adoption of Self-Service Technologies: Integrating the Behavioral Perspective with the Technology Acceptance Model

  • ASHOUR, Mohammed L.;AL-QIREM, Raed M.
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.3
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    • pp.1361-1369
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    • 2021
  • Recent technological advancements have had a substantial impact on consumer buying behavior. This research aims to determine the factors affecting consumer behavior related to the adoption of self-service technologies (SSTs). The intended findings of this study are expected to contribute to understanding consumer behavior towards the adoption of SSTs taking into account the logic of two main theories in this regard: the Technology Acceptance Model (TAM) and the assumptions of the Behavioral Perspective Model (BPM). This research follows a triangulation approach. Consequently, a number of semi structured interviews were conducted with experts and executive directors from selected SSTs providers in Jordan. In addition, the convenience sampling technique was employed focusing on current (or) previous users of SSTs in the public and private sectors in Jordan using a self-administrative questionnaire (66% response rate). The results confirmed the influence (direct and indirect) of previous experience and personal initiatives and characteristics on consumer intention to use SSTs. In addition, the results indicated the important role of the mediator variables namely: perceived ease of use (EOU), perceived risk (PR), and perceived usefulness (PU) on consumer attitude towards SSTs which in turn will positively affect consumer intention to use SSTs.

A Study on the Characteristics of 2-Dimensinal Molybdenum Disulfide Thin Films formed on Sapphire Substrates by DC Sputtering and Rapid Thermal Annealing (DC 스퍼터링 및 급속 열처리 공정을 이용한 사파이어 기판상에 형성된 2차원 황화몰리브덴 박막의 특성에 관한 연구)

  • Qi, Yuanrui;Ma, Sang Min;Jeon, Yongmin;Kwon, Sang Jik;Cho, Eou-Sik
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.3
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    • pp.105-109
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    • 2022
  • For the realization of higher reliable transition metal dichalcogenide layer, molybdenum disulfide was formed on sapphire substrate by direct current sputtering and subsequent rapid thermal annealing process. Unlike RF sputtered MoS2 thin films, DC sputtered showed no irregular holes and protrusions after annealing process from scanning electron microscope images. From atomic force microscope results, it was possible to investigate that surface roughness of MoS2 thin films were more dependent on DC sputtering power then annealing temperature. On the other hand, the Raman scattering spectra showed the dependency of significant E12g and A1g peaks on annealing temperatures.

A Study on the Efficiency Effects of Capping Layer on the Top Emission Organic Light Emitting Diode (전면 유기발광 다이오드 기능층 캐핑레이어 적용에 따른 효율상승에 관한 연구)

  • Lee, DongWoon;Cho, Eou Sik;Jeon, Yongmin;Kwon, Sang Jik
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.3
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    • pp.119-124
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    • 2022
  • Top emission organic light-emitting diode (TEOLED) is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device (BEOLED). Unlike BEOLED, TEOLED contain semitransparent metal cathode and capping layer. Because there are many characteristics to consider just simple thickness change, optimizing organic thickness of TEOLED for microcavity is difficult. So, in this study, we optimized Device capping layer at unoptimized micro-cavity structure TEOLED device. And we compare only capping layer with unoptimized microcavity structure can overcome optimized micro-cavity structure device. We used previous our optimized micro-cavity structure to compare each other. As a result, it has been found that the efficiency can be obtained almost the same or higher only capping layer, which is stacked on top of the device and controls only the thickness and refractive index, without complicated structural calculations. This means that higher efficiencies can be obtained more easily in laboratories with limited organic materials or when optimizing new structures etc.

Optimization of Mg:Ag Cathodes and Effect of LiF Electron Injection Layer on the Characteristics of Top Emission Organic Light Emitting Diodes (전면 유기발광 다이오드 제작시 Mg:Ag 캐소드 최적화 및 LiF 전자주입층 유무에 따른 소자 특성에 관한 연구)

  • Song, Min Seok;Kwon, Sang Jik;Cho, Eou-Sik
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.1
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    • pp.71-74
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    • 2022
  • For the process simplification in the fabrication of organic light emitting diode(OLED), top emission OLED (TEOLED) was fabricated without lithium fluoride(LiF) used as an electron injection layer (EIL). After co-deposition of Mg and Ag with a different process conditions, a cathode material adjacent to EIL was optimized when Mg and Ag have a ratio of 1:9 considering sheet resistance and transmittance. From the energy band diagram of TEOLED, band gap difference between Trisaluminium (Alq3) and Mg:Ag cathode show the difference of 0.4 eV according to the usage of LiF The fabricated TEOLED without LiF showed the improvement of 5.2 % and 2.7 % in the luminance and the current density comparing that with LiF. The results show there is no significant difference in OLED characteristics regardless of LIF layer in the TEOLED structures.

A Study on the Effects of Micro Cavity on the HTL Thicknesses on the Top Emission Organic Light Emitting Diode (유기발광 다이오드의 정공수송층 두께에 따른 미소 공진 효과의 영향에 관한 연구)

  • Lee, DongWoon;Cho, Eou Sik;Seong, Jin-Wook;Kwon, Sang Jik
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.1
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    • pp.91-94
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    • 2022
  • Top emission organic light-emitting diode is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device. Unlike BEOLED, TEOLED contain semi-transparent metal cathode. Because of semi-transparent cathode, micro cavity effect occurs in TEOLED. We optimized this effect by changing the thickness of hole injection layer. Device consists of is indium-tin-oxide / N,N'-Di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine (x nm) / tris-(8-hydroxyquinoline) aluminum (50nm) / LiF(0.5nm) / Mg:Ag (1:9), and we changed NPB thickness which is used as HTL in our device in order to study how micro cavity effects are changed by optical path. As the results, NPB thickness at 35nm showed the current efficiency of 8.55Cd/A.

A Study on the Thickness Dependence of p-type Organic Layer on the Current of Small Molecule-based Organic Photodiode (저분자 유기 광다이오드 소자의 p형 유기물 두께에 따른 전류 특성에 관한 연구)

  • Young Woo Kim;Dong Woon Lee;Yongmin Jeon;Eou-sik Cho;Sang Jik Kwon
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.3
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    • pp.101-105
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    • 2023
  • Organic photo Diodes (OPDi) give multiple advantages in the growing interest of the flexible optoelectronic devices. Organic semiconductors are freeform as they can deposit on any substrate, so it could be flexible. But the inorganic material photodiodes (PDs) are usually fabricated on silicon wafers which are solid. So, normally PDs are inflexible. By those reasons, we decided to make the vacuum deposited small molecule OPDi. We have investigated the OPDi's J-V characteristic by changing the thickness of p-type layer of OPDi. This device consists of indium-tin-oxide (ITO) / 2,3:6,7-dibenzanthracene (pentacene) / buckminsterfullerene (C60) / aluminum (Al). Its J-V characteristics were measured in the probe station(4156C) that can give dark condition while measuring. And for the luminance characteristics, the photocurrent was measured with the bright halogen lamp and a probe station.

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A Study on Vacuum-deposited Transparent OLED to Improve Its Transmittance and Luminescence Characteristics with a Mesh Electrode (진공 증착 투명 OLED 투과도 및 발광 특성 개선을 위한 Mesh 전극 연구)

  • Young Woo Kim;Yongmin Jeon;Eou-Sik Cho;Sang Jik Kwon
    • Journal of the Semiconductor & Display Technology
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    • v.23 no.2
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    • pp.82-86
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    • 2024
  • With the growing field and growing interest in transparent organic light-emitting diodes (TOLED) in the industry, various attempts are being made to improve the transmittance and performance of TOLED. TOLEDs are expected to be used in next-generation displays such as mixture reality (MR) displays, displayable windows, televisions, etc. This study presents a mesh TOLED with better transmittance and luminescence characteristics than existing TOLEDs through an in-situ vacuum deposition method that does not require additional processes such as photolithography and etching. In this study the mesh TOLED's cathode consists of Mg: Ag 1:9 electrode. Mesh patterns are interconnected with a 6 nm layer of interlayer. We approached transmittance improvement up to 30% at 555 nm at the cathode electrode with similar current injection character, also we improved lumination characteristics up to 23% at 7 V driving condition.

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