• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.717-720
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• 2002

In this work, the electrical characteristics of organic thin film transistors with the surface-treated organic gate insulators have been studied. For the surface treatment, the simple rubbing technique was used. The field effect mobilities of the devices with PVP gate insulator was improved about four times as high as those of TFTs without the insulator surface treatment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.96-96
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• 2007

Low voltage organic TFTs (OTFTs) and ZnO based TFTs (<5V), utilizing room temperature deposited $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN) thin films were recently reported, pointing to high-k gate insulators as a promising route for realizing low voltage operating flexible electronics. $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN) thin film is one of the most promising materials for gate insulator because of its large dielectric constant (~60) at room temperature. However their tendency to suffer from relatively high leakage current at low electric field (>0.3MV/cm) hinder the application of BZN thin films for gate insulator. In order to improve leakage current characteristics of BZN thin film, we mixed 30mol% MgO with 70mol% BZN and their dielectric and electric properties were characterized. We fabricated field-effect transistors with transparent oxide semiconductor ZnO serving as the electron channel and high-k $(Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7)_{0.7}(MgO)_{0.3}$ as the gate insulator. The devices exhibited low operation voltages (<4V) due to high capacitance of the $(Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7)_{0.7}(MgO)_{0.3}$ dielectric.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1044-1045
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• 2004

In this work, the characteristics of organic thin film transistors (OTFTs) with self-assembled monolayers (SAMs) on polymeric gate insulator have been investigated. The SAMs were formed using atomic layer deposition (ALD) method onto gate insulator. Upon the investigations, it was observed that SAMs modify the wettability of polymeric insulator and influence the growth of subsequent organic semiconductor, and thereby, electric conductivity and roughness of the pentacene film are improved.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1315-1318
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• 2007

Hafnium dioxide nano film as gate insulator for organic thin film transistors is prepared by atomic layer deposition. Mostly crystalline of $HfO_2$ films can be obtained with oxygen plasma and with water at relatively low temperature of $150^{\circ}C$. $HfO_2$ was deposited as a uniform rate $1.2A^{\circ}/cycle$. The morphology and performances of OTFT will be discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.185-190
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• 2003

In this paper, it was demonstrated that the organic thin film transistors were fabricated by the organic gate insulators with vapor deposition polymerization (VDP) processing. In order to form polyimide as a gate insulator, vapor deposition polymerization process was also introduced instead of spin-coating process, where polyimide film was co-deposited by high-vacuum thermal evaporation from 4,4'-oxydiphthalic anhydride (ODPA) and 4,4'-oxydianiline (ODA) and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and ODA, and cured at $150^{\circ}C$ for 1hr. Electrical output characteristics in our organic thin film transistors using the staggered-inverted top-contact structure obtained to the saturated slop in the saturation region and the subthreshold non-linearity in the triode region. Field effect mobility, threshold voltage, and on-off current ratio in $0.45\;{\mu}m$ thick gate dielectric layer were about $0.17\;cm^2/Vs$, -7 V, and $10^6\;A/A$, respectively. Details on the explanation of compared to organic thin-film transistors (OTFTS) electrical characteristics of ODPA-ODA and 6FDA-ODA as gate insulators by fabricated thermal co-deposition method.

• 한국재료학회지
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• 제28권4호
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• pp.247-253
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• 2018

We examined the characteristics of indium tin zinc oxide (ITZO) thin film transistors (TFTs) on polyimide (PI) substrates for next-generation flexible display application. In this study, the ITZO TFT was fabricated and analyzed with a SiOx/SiNx gate insulator deposited using plasma enhanced chemical vapor deposition (PECVD) below $350^{\circ}C$. X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) results revealed that the oxygen vacancies and impurities such as H, OH and $H_2O$ increased at ITZO/gate insulator interface. Our study suggests that the hydrogen related impurities existing in the PI and gate insulator were diffused into the channel during the fabrication process. We demonstrate that these impurities and oxygen vacancies in the ITZO channel/gate insulator may cause degradation of the electrical characteristics and bias stability. Therefore, in order to realize high performance oxide TFTs for flexible displays, it is necessary to develop a buffer layer (e.g., $Al_2O_3$) that can sufficiently prevent the diffusion of impurities into the channel.

• 한국진공학회지
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• 제13권3호
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• pp.99-102
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• 2004

유기 절연층을 사용한 유기 박막 트랜지스터의 특성 향상을 위해 절연층 표면에 Ar플라즈마 처리를 하였다. 플라즈마 처리는 절연체 표면의 화학적, 물리적 특성 변화를 통해 그 후에 이어지는 활성층 성막시 분자들의 결정성을 향상시키기 위한 방법이다. 활성층으로 사용된 물질은 pentacene이며, 절연층으로 사용된 물질은 PVP(poly-vinyl-phenol)이다. Pentacene는 약 $10^{-6}$ Torr에서 0.5 $\AA$/sec의 속도로, PVP는 spin coating법에 의해 각각 성막되었다. 형성된 절연층을 일정 시간동안 H플라즈마 처리 한 후 각 소자의 전기적 특성을 측정하여 표면처리에 의한 특성 변화를 살펴보았다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권12호
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• pp.755-760
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• 1999

Various fluoride films were investigated for a gate insulator of thin film transistor application. Conventional oxide containing materials like $SiO_2\;Ta_2O_5\; and \; Al_2O_3$ exhibited high interface states which lead to an increased threshold voltage and poor stability of TFT. In this paper, we investigated gate insulators using a binary matrix system of fluoride such as $CaF_2,\; SrF_2\; MgF_2,\; and\; BaF_2$. These materials exhibited an improvement in lattice mismatch, interface state and electrical stability. MIM and MIS devices were employed for an electrical characterization and structural property examination. Among the various fluoride materials, $CaF_2$ film showed an excellent lattice mismatch of 5%, breakdown electric field higher than 1.2MV/cm and leakage current density of $10^{-7}A/cm^2$. MIS diode having $Ca_2$ film as an insulation layer exhibited the interface states as low as $1.58\times10^{11}cm^{-2}eV^{-1}$. This paper probes a possibility of new gate insulator materials for TFT applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1434-1435
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• 2006

본 연구에서는 polymer gate insulators에 따른 pentacene 유기 박막 트랜지스터 (Organic Thin-Film Transistors)의 전기적 특성을 atom force microscope (AFM), x-ray diffraction (XRD) 그리고 I-V 측정을 이용하여 분석하였다. Pentacene 박막 트랜지스터의 전기적 특성은 pentacene의 증착 조건뿐만 아니라 polymer gate insulator에 따라 크게 영향을 받는다. 따라서 다양한 polymer 기판 위에 온도, 두께 그리고 증착 속도에 따라 pentacene을 증착 하였다. 그리고 증착된 pentacne을 AFM, XRD를 이용하여 pentacene의 구조, 결정화 그리고 grain 크기 등을 분석하였다. 또한 inverted stagger며 구조의 pentacene 박막 트랜지스터 소자를 제작하고 I-V 측정하여 그 결과를 분석하였다.

• ETRI Journal
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• 제31권1호
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• pp.62-64
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• 2009

We report on the bias stability characteristics of transparent ZnO thin film transistors (TFTs) under visible light illumination. The transfer curve shows virtually no change under positive gate bias stress with light illumination, while it shows dramatic negative shifts under negative gate bias stress. The major mechanism of the bias stability under visible illumination of our ZnO TFTs is thought to be the charge trapping of photo-generated holes at the gate insulator and/or insulator/channel interface.