• Title/Summary/Keyword: Optical mobility

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Transparent ZnO based thin film transistors fabricated at room temperature with high-k dielectric $Gd_2O_3$ gate insulators

  • Tsai, Jung-Ruey;Li, Chi-Shiau;Tsai, Shang-Yu;Chen, Jyun-Ning;Chien, Po-Hsiu;Feng, Wen-Sheng;Liu, Kou-Chen
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.374-377
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    • 2009
  • The characteristics of the deposited thin films of the zinc oxide (ZnO) at different oxygen pressures will be elucidated in this work. The resistivity of ZnO thin films were dominated by the carrier concentration under high oxygen pressure conditions while controlled by the carrier mobility at low oxygen ambiences. In addition, we will show the characteristics of the transparent ZnO based thin film transistor (TFT) fabricated at a full room temperature process with gate dielectric of gadolinium oxide ($Gd_2O_3$) thin films.

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Fabrication of FIPOS-SOI Using $n/p^+/p$ Structure ($n/p^+/p$구조를 이용한 FIPOS-SOI의 제조)

  • 양천순;이종현
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.12
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    • pp.2010-2015
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    • 1989
  • A SOI was fabricated by the FIPOS technique using n/p+/p silicon structure. Fabricated silicon island which has 3\ulcorner thickness and 100\ulcorner width was investigated by measuring van der Pauw resistivity, Hall mobility, dielectric breakdown voltage and leakage current. Hall mobility of the SOI was measured to be 300-500cm\ulcornerV.sec and its breakdown field was 1-2 MV/cm. The cross-sectional geometries of the SOI island were examined by SEM and optical microscope.

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Effects of Ag Additives on Electrical and Optical Properties of As2Se3 Thin Films (비정질 As2Se3 박막에 첨가된 은이 전기 및 광학적 성질에 미치는 효과)

  • Lee, Chanku;Lee, Sudae;Kim, Douk Hoon;Mun, Jung Hak
    • Journal of Korean Ophthalmic Optics Society
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    • v.1 no.2
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    • pp.63-69
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    • 1996
  • D.c conductivity and optical transmittance of amorphous ($As_2Se_3$)Ag, (x =0, 2, 5, 10mol%) thin films were measured in order to find effects of Ag additives on electrical and optical properties of the films. The d.c. activation energy and the optical gap decreased with increasing Ag contents the Urbach tail was approximately unchangeable for variation of Ag contents. For Ag contents of 5mol% and less, the rate of decrease of the d.c activation energy was more rapidly than that of the optical gap with increasing Ag contents. For Ag contents more than 5mol%, the rate of decrease of the d.c activation energy and the optical gap were nearly the same each other with decreasing Ag contents. So it was appeared that the Fermi level of the films comes close to the mobility edge for Ag contents of 5mol% and less, and the mobility edge comes close the Fermi level for Ag contents more than 5mol%.

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Improvement of Optical and Electrical Properties of ITO/Ag/ITO Thin Films for Transparent Conducting Electrode (투명 전극 ITO/Ag/ITO 박막의 광학적 및 전기적 특성 향상 연구)

  • Shin, Yeon Bae;Kang, Dong-Won;Kim, Jeha
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.11
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    • pp.740-744
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    • 2017
  • Herein we studied the electrical and optical properties of indium tin oxide ITO/Ag/ITO multilayer thin films for application in transparent conducting electrodes. The ITO and Ag thin films were deposited onto soda lime glass (SLG) using radiofrequency and DC-sputtering methods, respectively. The as-synthesized ITO/Ag/ITO multilayer thin films were analyzed using 4-point probe, UV-Visible spectroscopy, and Hall measurement. We observed a rapid increase in electron concentration with increasing Ag thickness. However, electron mobility decreased with increasing Ag thickness. Finally, ITO/Ag/ITO multilayer thin films showed a characteristic low sheet resistance of $18{\Omega}/sq$ and high optical transmittance value (80%) with variation of Ag thickness (5~10 nm).

Structural, Electrical, and Optical Properties of AGZO Thin Films Using RF Magnetron Sputtering System Under Ar Flow Rates (RF 마그네트론 스퍼터링 시스템을 이용하여 증착한 AGZO 박막의 Ar 유량에 따른 구조적, 전기적, 광학적 특성)

  • Jang, Seok-Hyeon;Kim, Deok Kyu
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.1
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    • pp.32-36
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    • 2022
  • AGZO thin films were deposited on glass substrates using RF magnetron sputtering system under Ar flow rates, and their structural, electrical, and optical properties were analyzed systematically. As a result of the XRD pattern, the peak of the (002) (2θ≈33.7˚) orientation was observed, and it was found to have a hexagonal wurtzite structure. The sheet resistance of Ar 5 sccm was 3.073×102 Ω/sq and showed the best electrical properties because of the improvement of mobility due to the increase of the grain size and the variation of RMS roughness. In addition, the average transmittance was more than 90% for all samples, which demonstrated good optical properties. It is expected that the TCO characteristics can be improved by controlling Ar flow rates, and this will increase the efficiency of photoelectronic devices such as OLED and solar cells.

Application of Nd-YAP laser to the conventional treatment of periodontal and endodontic combined lesions (Nd-YAP laser를 적용한 치주-근관 복합병소의 치료에 대한 고찰)

  • Kang, He-Kyong;Yoon, Ho-Jung
    • The Journal of the Korean dental association
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    • v.47 no.8
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    • pp.479-486
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    • 2009
  • Purpose: The aim of this study was to show the clinical results of combination of Nd-YAP (1340nm) laser therapy with conventional endodontic and periodontal treatment. Materials and Methods: Four patients with chronic advanced periodontitis and endodontic infection were treated with conventional treatment and Nd-YAP laser therapy. Occlusal adjustment and splinting were done for stabilization of the teeth with severe horizontal and vertical mobility. The protocol for periodontal treatment was followed as scaling and root planing, pocket irrigation with 3% $H_2O_2$ and exposure of Nd-YAP laser using 320${\mu}m$ optical fiber with 160mJ/pluse, 30Hz. The other protocol for endodontic treatment was followed as access opening, canal preparation by hand and rotary instrument, canal filling, and exposure of Nd-YAP laser using 200${\mu}m$ optical fiber with 200mJ/pluse, 10Hz and 180mJ/pluse, 5Hz which were used respectively for disinfection and canal filling. The assessments of probing depth, mobility, and radiography were made prior to and after treatment. Result: All of these four clinical cases showed good healing of periodontium, which presented decrease of mobility and pocket depth, and increase of bone regeneration and bone density on the radiography. Conclusion: The bactericidal effect of Nd-YAP laser would provide benefits for improving clinical results that are obtained from conventional therapy.

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Effect of Work Function of Zn-doped ITO Thin Films on Characteristics of Silicon Heterojunction Solar Cells (실리콘 이종접합 태양전지 특성에 대한 Zn 도핑된 ITO 박막의 일함수 효과)

  • Lee, Seung-Hun;Tark, Sung-Ju;Choi, Su-Young;Kim, Chan-Seok;Kim, Won-Mok;Kim, Dong-Hhwan
    • Korean Journal of Materials Research
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    • v.21 no.9
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    • pp.491-496
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    • 2011
  • Transparent conducting oxides (TCOs) used in the antireflection layer and current spreading layer of heterojunction solar cells should have excellent optical and electrical properties. Furthermore, TCOs need a high work function over 5.2 eV to prevent the effect of emitter band-bending caused by the difference in work function between emitter and TCOs. Sn-doped $In_2O_3$ (ITO) film is a highly promising material as a TCO due to its excellent optical and electrical properties. However, ITO films have a low work function of about 4.8 eV. This low work function of ITO films leads to deterioration of the conversion efficiency of solar cells. In this work, ITO films with various Zn contents of 0, 6.9, 12.7, 28.8, and 36.6 at.% were fabricated by a co-sputtering method using ITO and AZO targets at room temperature. The optical and electrical properties of Zn-doped ITO thin films were analyzed. Then, silicon heterojunction solar cells with these films were fabricated. The 12.7 at% Zn-doped ITO films show the highest hall mobility of 35.71 $cm^2$/Vsec. With increasing Zn content over 12.7, the hall mobility decreases. Although a small addition of Zn content increased the work function, further addition of Zn content over 12.7 at.% led to decreasing electrical properties because of the decrease in the carrier concentration and hall mobility. Silicon heterojunction solar cells with 12.7 at% Zn-doped ITO thin films showed the highest conversion efficiency of 15.8%.

Optical Disc System Controller Design Based on a Disturbance Detector (외란 검출기에 기반한 광디스크 시스템 제어기 설계)

  • Choi, Byung-Ho;Choi, Ga-Hyung;Yoon, Tae-Sung;Park, Jin-Bae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.8
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    • pp.1595-1604
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    • 2009
  • An Optical disk driver is used in many electronic products besides the computers. In particular, the demands are recently increased as an optical disk player/recorder in the mobile products such as camcorder, portable player or in the home theater appliances, etc. However, the more the mobility is emphasized, the more the optical disk player is exposed to the disturbance inputs. For reducing the possibility of malfunction of the optical disk, we propose a nonlinear controller using the disturbance detecting algorithm based on the Kalman filter. Actual experiments were executed to verify the performance of the proposed method. The proposed method controls the tracking error signal within ${\pm}0.1{\mu}m$.

Synthesis of New Blue OLEDs with Biphenyl Structure and Relationship between EL Efficiency and Drift Mobility (Biphenyl 구조를 가진 새로운 청색 유기 발광 재료의 합성 및 EL효율과 이동도의 관계에 대한 연구)

  • Lee, Tae-Hoon;Ryu, Jung-Yi;Kim, Tae-Hoon;Nam, Jang-Hyun;Park, Seong-Soo;Son, Se-Mo
    • Journal of the Korean Graphic Arts Communication Society
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    • v.22 no.2
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    • pp.179-198
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    • 2004
  • Organic electroluminescent devices are light-emitting diodes in which the active materials consist entirely of organic materials. Recently, many fluorescent organic materials have been reported and the study on synthesis and application of new organic light-emitting materials has been demanded. This paper reports the optical and electrical characteristics of OLEDs using novel polymers containing biphenyl structure. First, Optical properties of novel light-emitting biphenyl derivatives doped with poly(9-vinyl carbazole)(PVK) and emitted blue, bluish green color, which is attributed to the overlap area between PL spectrum of host(PVK) and absorption spectra of guests(polymer). This is correspondent with F$\"{o}$rster energy transfer process in the blends. And, OLED devices were fabricated using poly (3,4-ethylenedioxy thiophene) (PEDOT) as a hole injection material and tris-(8-hydroxyquinoline) aluminum ($Alq_3$) as an electron transporting material. EL devices fabricated as ITO/PEDOT/PVK doped with biphenyl derivatives/$Alq_3$/Li:Al and I-V-L chatacteristics and emitting efficiency of EL devices were examined. Finally, the drift mobility of PVK doped with biphenyl derivatives and $Alq_3$ were measured by TOF technique varying applied electric field. EL efficiency was increased as the ratio of hole mobility of PVK doped with biphenyl derivatives and electron mobility of $Alq_3$ was close to one.

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Conformal Zinc Oxide Thin Film Deposition on Graphene using molecular linker by Atomic Layer Deposition

  • Park, Jin-Seon;Han, Gyu-Seok;Jo, Bo-Ram;Seong, Myeong-Mo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.280.2-280.2
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    • 2016
  • The graphene, a single atomic sheet of graphite, has attracted tremendous interest owing to its novel properties including high intrinsic mobility, optical transparency and flexibility. However, for more diverse application of graphene devices, it is essential to tune its transport behavior by shifting Dirac Point (DP) of graphene. So, in the following context, we suggest a method to tune structural and electronic properties of graphene using atomic layer deposition. By atomic layer deposition of zinc oxide (ZnO) on graphene using 4-mercaptophenol as linker, we can fabricate n-doped graphene. Through ${\pi}-{\pi}$ stacking between chemically inert graphene and 4-mercaptophenol, conformal deposition of ZnO on graphene was enabled. The electron mobility of graphene TFT increased more than 3 times without considerably decreasing the hole mobility, compared to the pristine graphene. Also, it has high air stability. This ZnO doping method by atomic layer deposition can be applicable to large scale array of CVD graphene TFT.

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