• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.265.2-265.2
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• 2016

Oxide thin film transistors (TFTs) have attracted considerable interest for gate diver and pixel switching devices of the active matrix (AM) liquid crystal display (LCD) and organic light emitting diode (OLED) display because of their high field effect mobility, transparency in visible light region, and low temperature processing below $300^{\circ}C$. Recently, oxide TFTs with polycrystalline In-Ga-O(IGO) channel layer reported by Ebata. et. al. showed a amazing field effect mobility of $39.1cm^2/Vs$. The reason having high field effect mobility of IGO TFTs is because $In_2O_3$ has a bixbyite structure in which linear chains of edge sharing InO6 octahedral are isotropic. In this work, we investigated the characteristics and the effects of oxygen partial pressure significantly changed the IGO thin-films and IGO TFTs transfer characteristics. IGO thin-film were fabricated by rf-magnetron sputtering with different oxygen partial pressure ($O_2/(Ar+O_2)$, $Po_2$)ratios. IGO thin film Varies depending on the oxygen partial pressure of 0.1%, 1%, 3%, 5%, 10% have been some significant changes in the electrical characteristics. Also the IGO TFTs VTH value conspicuously shifted in the positive direction, from -8 to 11V as the $Po_2$ increased from 1% to 10%. At $Po_2$ was 5%, IGO TFTs showed a high drain current on/off ratio of ${\sim}10^8$, a field-effect mobility of $84cm^2/Vs$, a threshold voltage of 1.5V, and a subthreshold slpe(SS) of 0.2V/decade from log(IDS) vs VGS.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.6
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• pp.17-23
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• 2000

In this study, we prepared red organic light-emitting-diode(OLED) with a fluorescent dye(Sq)-doped and inserted between emission and cathode layer 1,3-bis(5-p-t-butylphenyl)-1,3,4-oxadiazol-2-yl)benzene (OXD7) or/and tris(8-hydroxyquinoline) aluminum ($Alq_3$) layers for increasing electroluminescent(EL) efficiency. This inserting effect has been observed and EL mechanism characteristics have been examined. The hole transfer layer is a N,N'-diphenyl-N,N'-bis-(3-methyl phenyl)-1,1'-diphenyl-4,4'-diamine (TPD), and the host and guest materials of emission layer is $Alq_3$ and bis[1-methyl-3,3'-dimethyl-2-indorindiylmethyl] squaraine (Sq), respectively. For the inserting of $Alq_3$, emission efficiency increased. But we can not obtained highly pure red emission owing to the emission of inserting $Alq_3$ layer. The inserting of OXD7 makes hole block and accumulate. Because of increasing recombination probability of electron and hole, highly pure red color can be held. Simultaneously brightness characteristics and emission efficiency could improve.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.238-238
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• 2012

Ag (silver)의 일함수는 T-OLED (Top Emission Organic Light Emitting Diode)의 전극소자로 사용하기에는 다소 낮다는 단점이 있다(~4.3 eV). 이러한 단점을 해결하기 위한 대안으로 Ag 박막의 표면을 플라즈마 처리, UV 처리 및 열처리를 통하여 일함수를 높이는 연구가 진행 되어왔다(>5.0 eV). 하지만 현재의 대부분 연구는 후 처리된 박막의 일함수에 초점을 맞춰 연구가 진행 되어 박막의 nano-mechanical property에 대한 연구는 매우 부족하다. 따라서 본 논문에서는 AgOx 박막의 nano-mechanical property에 초점을 맞춰 분석을 실시하였다. 연구에 사용된 샘플은 Ag 박막을 유리기판 위에 rf-magnetron sputter 장치를 이용하여 100 W의 power로 150 nm 두께로 증착하였다. 증착된 Ag 박막은 $O_3$ 발생 UV 램프를 이용하여, 다양한 시간동안 UV 처리하였다(0~9분). 증착된 샘플은 Four-point probe, nanoindenter 장비를 이용하여 nano-mechanical property를 분석하였다. 실험 결과 UV 처리 시간이 0, 1분에서 면저항이 0.16, 0.50 ${\Omega}$/sq로 급격한 변화가 나타났으나, 반면 3분 이후 9분의 샘플의 경우, 0.55 ${\Omega}$/sq에서 0.24, 0.20, 0.15 ${\Omega}$/sq로 감소하여 전기적 특성변화를 볼 수 있었다. 또한 nanoindenting 결과 UV 처리한 박막의 극 표면 경도 값의 변화는 0~5분 처리한 샘플의 경우, 물리적인 경도가 증가하는 형태를 보이며 UV 처리를 5분간 했을때 7.89 GPa로 최고의 경도를 가진다. 그 이후부터는 6.97, 3.46 GPa의 결과로 박막의 경도가 감소되는 결과를 얻었다. 이러한 결과로부터 Ag 박막의 후처리에 따른 Ag 물질의 산화 및 결정상태에 따라 박막 내에 존재하는 residual stress를 분석할 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.418-419
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• 2013

현재, 인듐 주석 산화물(indium tin oxide, ITO) 박막은 가시영역에서 전기적 특성 및 광학적 특성이 우수하기 때문에 평면 디스플레이(flat displays), 박막 트랜지스터(thin film transistors), 태양전지(solar cells) 등을 포함한 광소자에 투명전도성산화물(transparent conducting oxide, TCO) 전극으로 가장 일반적으로 사용되고 있다. 하지만, 이 물질은 밴드갭이 3.4 eV로 다소 작아 다양한 분야의 의료기기, 환경 보호에 응용 가능한 자외선 영역에서 상당히 많은 양의 광흡수가 발생하는 치명적인 문제점을 가지고 있다. 또한, 인듐(Indium)의 급속한 소비는 인듐의 매장량의 한계로 인해 가격을 상승시키는 주요한 원인으로 작용하고 있다. 한편, InGaN 기반의 자외선 발광다이오드 분야에서는 팔라듐(Pd) 기반의 반투명 전극과 은(Ag) 기반의 반사전극을 주로 사용하고 있지만, 낮은 투과도와 낮은 굴절률을 때문에 여전히 자외선 발광다이오드의 광추출 효율(extraction efficiency)에 문제점을 가지고 있다. 따라서 자외선 발광다이오드의 외부양자 효율(external quantum efficiency, EQE)을 높이기 위해 높은 투과도와 GaN와 유사한 굴절률을 가지는 p-형 오믹 전극을 개발해야 한다. 본 연구에서는 초박막의 ITO (16 nm)/Ag (7 nm)/ITO (16 nm) 다층 구조를 갖는 투명전도성 전극을 제작한 후, 열처리 온도에 따른 전기, 광학적 특성에 향상에 대해서 조사하였다. 사용된 산화물/금속/산화물 전극의 구조는 유기발광 다이오드(organic light emitting diode, OLED), 태양전지 등에 많이 사용되는 안정적인 투명 전극을 자외선 LED 소자에 처음 적용하여, ITO의 전체 사용량은 줄이고, ITO 사이에 금속을 삽임함으로써 금속에 의한 전기적 특성 향상과 플라즈몬 효과에 의한 투과도를 높일 수 있는 장점을 가지고 있다. 실험 결과로는, $400^{\circ}C$에서 열처리한 ITO/Ag/ITO 다층 구조는 365 nm에서 84%의 광학적 특성과 9.644 omh/sq의 전기적 특성을 확인하였다. 실험 결과로부터 좀 더 최적화를 수행하면, ITO/Ag/ITO 다층 구조는 자외선 발광다이오드의 투명전도성 전극으로 사용될 수 있을 것이라 기대된다.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.647-650
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• 2006

Low temperature polycrystalline silicon (LTPS) technology using a high power laser have been widely applied to thin film transistors (TFTs) for liquid crystal, organic light emitting diode (OLED) display, driver circuit for system on glass (SOG) and static random access memory (SRAM). Recently, the semiconductor industry is continuing its quest to create even more powerful CPU and memory chips. This requires increasing of individual device speed through the continual reduction of the minimum size of device features and increasing of device density on the chip. Moreover, the flat panel display industry also need to be brighter, with richer more vivid color, wider viewing angle, have faster video capability and be more durable at lower cost. Kornic Systems Co., Ltd. developed the $KORONA^{TM}$ LTP/GLTP series - an innovative production tool for fabricating flat panel displays and semiconductor devices - to meet these growing market demands and advance the volume production capabilities of flat panel displays and semiconductor industry. The $KORONA^{TM}\;LTP/GLTP$ series using DPSS laser and XeCl excimer laser is designed for the new generation of the wafer & FPD glass annealing processing equipment combining advanced low temperature poly-silicon (LTPS) crystallization technology and object-oriented software architecture with a semistandard graphical user interface (GUI). These leading edge systems show the superior annealing ability to the conventional other method. The $KORONA^{TM}\;LTP/GLTP$ series provides technical and economical benefits of advanced annealing solution to semiconductor and FPD production performance with an exceptional level of productivity. High throughput, low cost of ownership and optimized system efficiency brings the highest yield and lowest cost per wafer/glass on the annealing market.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.148-154
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• 2010

We have fabricated $SiO_2$ oxidation thin films by TCP-CVD (transformer coupled plasma chemical vapor deposition) method for passivation layer of OLED (organic light emitting diode). The purpose of this paper is to control and estimate the deposition rate and refracive index characteristics with process parameters. They are power, gas condition, distance of source and substrate and process temperature. The results show that transmittance of thin films is over 90%, rapid deposition rate and stable reflective index from 1.4 to 1.5 at controled process conditions. They are $SiH_4$ : $O_2$ = 30 : 60 [sccm] gas condition, 70 [mm] distance of source and substrate, no-biased substrate and under 80 [$^{\circ}C$] process temperature.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.157-160
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• 2021

As an insulator for a thin film transistor(TFT) and an encapsulation material of organic light emitting diode(OLED), aluminum oxide (Al₂O₃) has been widely studied using several technologies. Especially, in spite of low deposition rate, atomic layer deposition (ALD) has been used as a process method of Al₂O₃ because of its low process temperature and self-limiting reaction. In the Al₂O₃ deposition by ALD method, Ar Purge had some crucial effects on the film properties. After reaction gas is injected as a formation of pulse, an inert argon(Ar) purge gas is injected for gas desorption. Therefore, the process parameter of Ar purge gas has an influence on the ALD deposited film quality. In this study, Al₂O₃ was deposited on glass substrate at a different Ar purge time and its structural characteristics were investigated and analyzed. From the results, the growth rate of Al₂O₃ was decreased as the Ar purge time increases. The surface roughness was also reduced with increasing Ar purge time. In order to obtain the high quality Al₂O₃ film, it was known that Ar purge times longer than 15 sec was necessary resulting in the self-limiting reaction.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.418-423
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• 2009

MWCNT(multi-wall carbon nanotube)-doped PEDOT:PSS(poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), used as a HIL(hole injection layer) material in OLEDs(organic light emitting diodes), was spin-coated on to the ITO glass to form PEDOT:PSS-MWCNT nano composite thin film. Morphology and transparency characteristics of nano composite thin films with respect to the loading percent of MWCNT have been investigated using FT-IR, UV-Vis and SEM. Furthermore, ITO/PEDOT:PSS-MWCNT/NPD/$Alq_3$/Al devices were fabricated, and then J-V and L-V characteristics were investigated. Functional group-incorporated MWCNT was prepared by acid treatment and showed good dispersion property in PEDOT:PSS solution. PEDOT:PSS-MWCNT thin films possessed good transparency property. For multi-layered devices, it was shown that as the loading percent of MWCNT increased, the current density increased but the luminance dramatically decreased. It might be conclusively suggested that the enhanced charge mobility by MWCNT could increase the current density but the hole trapping property of MWCNT could dramatically decrease the hole mobility in the current devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.878-885
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• 2008

The FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) and OLED(Organic Light Emitting Diode), recently, have been substituted for CRT(Cathode Ray Tube) displays because they have a convex surface, small volume, light weight and lower electric power consumption. The productivity of FPDs is greatly dependent on the area of thin glass panel with 0.6 - 0.8mm thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass panel. For example, the thin glass panel size of the 8th generation is 2,200mm in width, 2,600mm in length and 0.7mm in thickness. The air flows both in the thin glass panel and in the porous PE-plate surface were modeled and analyzed, from which a working condition was estimated. The thin glass panel on the porous PE-plate surface with self-lubricating characteristics was investigated and compared with that on the square duct floating bar surface with many holes of 1mm diameter when the thin glass panel contacts the floating bar surface due to malfunction of electric power supply.