• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.27-31
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• 2007

The cpapcitors with MIM(metal-insulator-metal) structures using PVP gate insulation films were prepared for the application of flexible organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as a solute and PGMEA(propylene glycol monomethyl ether acetate) as a solvent. The cross-linked PVP insulation films were also prepared by addition of poly(melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross- linked PVP films was found to be about 1.3 nA on Al/PES(polyethersulfone) substrate, whereas, on ITO/ glass substrate was about 27.5 nA indicating improvement of the leakage current at Al/PES substrates. Also, the capacitances of all prepared samples on ITO/glass and Al/PES substrates w ere ranged from 1.0 to $1.2nF/cm^2$, showing very similar result with the calculated capacitance values.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.571-574
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• 2009

Metal oxide/metal bilayer structures are explored as contacts with a low injection barrier in organic thin-film transistors (OTFTs) in an effort to realize their true potential for low-cost electronics. OTFTs with a bilayer electrode of $WO_3$ (10nm) and Al shows a saturation mobility as large as 0.97 $cm^2$/Vsec which are comparable to those of Au-based control samples (~0.90 $cm^2$/Vsec). Scaling of contact resistance with respect to the thickness of $WO_3$ layer is also discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.388-388
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• 2013

현대 사회에서 고집적 및 고성능의 전자소자의 필요성은 지속적으로 요구되고 있으며, 투명하거나 플렉서블한 특성의 필요성에 따라 이에 대한 기술개발이 이루어지고 있다. 특히, 이러한 특성을 만족하면서 대면적화 및 저온 공정의 특성을 지니는 유기물 반도체가 주목받고 있고, 이를 이용하여 OLED (Organic Light Emitting Diode), OTFT (Organic Thin Film Transistor)와 같은 다양한 유기물 반도체 소자가 개발되고 있다. 대표적인 예로는이 있다. 유기물 반도체 소자의 특성을 이용한 메모리 소자 또한 연구 및 개발이 지속되고 있으며, 유연성과 낮은 공정가격 등의 특성을 가지는 나노 입자들이 기존 Floating Gate의 대체물로 각광받고 있다. 본 논문에서는 MIS (Metal/Insulator/Semiconductor) 구조를 제작하고, Insulator 내부에Core/Shell 구조를 가지는 CdSe/ZnS 나노 입자를 부착하여 메모리 소자의 특성 확인 및 단위 면적당 개수에 따른 특성 변화를 확인하고자 하였다. 합성된 PVP (Poly 4-Vinyl Phenol)를 Insulator 층으로 사용하였으며 단위 면적당 나노 입자의 개수를 조절하여 제작된 MIS 소자를 Capacitance versus Voltage (C-V) 측정을 통하여 변화특성을 확인하였다.

• Journal of the Korean Applied Science and Technology
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• v.24 no.1
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• pp.54-60
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• 2007

이 논문에서는 게이트 절연막 위에 vapor deposition polymerization(VDP)방법을 사용하여 성막한 유기 점착층을 진공 열증착하여 유기 박막 트랜지스터(OTFTs)소자를 제작할 수 있음을 증명하였다. 우리가 제작한 Staggered-inverted top-contact 구조를 사용한 유기 박막 트랜지스터는 전기적 output 특성이 포화 영역안에서는 포화곡선을, triode 영역에서는 비선형적인 subthreshold를 확실히 볼 수 있음을 발견했다. $0.2{\mu}m$ 두께를 가진 게이트 절연막위에 유기 점착층을 사용한 OTFTs의 장 효과 정공의 이동도와 문턱전압, 그리고 절멸비는 각각, 약 0.4cm2/Vs, -0.8V, 106 이 측정되었다. 게이트 절연막의 점착층으로써 폴리이미드의 성막을 위해, 스핀코팅 방법 대신 VDP 방법을 도입하였다. 폴리이미드 고분자막은 2,2bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride(6FDA)와 4,4'-oxydianiline(ODA)을 고진공에서 동시에 열 증착 시킨 후, 그리고 $150^{\circ}C$에서 1시간, 다시 $200^{\circ}C$에서 1시간 열처리하여 고분자화된 막을 형성하였다. 그리고 점착층이 OTFTs의 전기적 특성에 주는 영향을 설명하기 위해 비교 연구하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1440-1442
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• 2005

We have fabricated vertical type organic thin film transistors (OTFTs) using organic semiconductor materials such as F16CuPc, NTCDA, PTCDI C-8 and C60. The layers of OTFT were fabricated by vacuum evaporation technique and spin casting method onto the Indium Tin Oxide (ITO) coated glass. I-V characteristics and on-off ratios of the fabricated OTFTs were investigated. In addition, we have fabricated light emitting transistor using MEH-PPV and then investigated EL electroluminescent properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.961-968
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• 2003

In order to reach the high electrical quality of organic thin film transistors (OTFTs) such as high mobility and on-off current ratio, it is strongly desirable to study the enhancement of electrical properties in OTFTs. Here, we report the novel method of hydrogen plasma treatment to improve electrical properties in inverted staggered OTFTs based on pentacene as active layer. To certify the effect of this method, we compared the electrical properties of normal device as a reference with those of device using the novel method. In result, the normal device as a reference making no use of this method exhibited a field effect mobility of 0.055 $\textrm{cm}^2$/Vs, on/off current ratio of 10$^3$, threshold voltage of -4.5 V, and subthreshold slope of 7.6 V/dec. While the device using the novel method exhibited a field effect mobility of 0.174 $\textrm{cm}^2$/Vs, on/off current ratio of 10$\^$6/, threshold voltage of -0.5 V, and subthreshold slope of 1.49 V/dec. According to these results, we have found the electrical performances in inverted staggered pentacene TFT owing to this method are remarkably enhanced. So, this method plays a key role in highly improving the electric performance of OTFTs. Moreover, this method is the first time yet reported for any OTFTs.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.420-425
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• 2012

The new organic semiconductors which are composed of divinylbenzene core unit and alkoxynaphthalene on both sides, 1,4-bis-2-(6-octyloxy)naphthalen-2-ylvinylbenzene (BONVB), 1,4-bis-2-(6-decyloxy)naphthalen-2-ylvinylbenzene (BDNVB) and 1,4-bis-2-(6-dodecyloxy)naphthalen-2-ylvinylbenzene (BDDNVB) were synthesized by Wittig reaction. The structures of obtained BONVB, BDNVB and BDDNVB were confirmed by FT-IR and mass spectroscopy. UV-absorption of thin film showed H-aggregates and J-aggregates due to closely packed structure between adjacent molecules. The characterization of vacuum-evaporated films by Xray diffraction (XRD) and atomic force microscopy (AFM) showed that the chain length of alkoxy group affects the crystallinity and morphology. BONVB with octyloxy group showed the mobility of $0.011cm^2/V{\cdot}s$, on/off ratio of $1.31{\times}10^5$, and a subthreshold slope of 0.93 V.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.136-138
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• 2007

본 연구에서는 유기박막트랜지스터 (OTFT, Organic Thin film Transistor) 제작을 위한 채널막으로 pentacene의 soluble 공정 과 soluble 공정 올 통하여 제작된 pentacene 박막의 특성 을 분석 하여 유기박막트랜지스터에 적용 여부를 조사하였다. Pentacene을 용해시키기 위한 용제로는 toluene과 chloroform을 사용하였으며, 각각의 용제에 대하여 열처리를 하여 pentacene 용액을 준비하였다. Spin-coating 법으로 pentacene 유기 박막을 제작하여 각 박막의 결정화 특성을 관찰하였다. XRD 회절 분석 결과 chloroform 올 이용한 pentacene 박막에서만 결정화가 된 것이 확인이 되었다. Hall effect measurement 분석 결과 chloroform올 이 용한, pentacene 박막의 전하농도 (Carrier Concentration)는 $-3.225{\times}1014(c{\cdot}cm^{-3})$를 나타내었고, 이동도 (Mobility)는 $3.5{\times}10^{-l}(cm^2{\cdot}V^{-1}{\cdot}S^{-1})$를 각각 나타내었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1413-1415
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• 2005

The OTFT performance depends strongly on the interfacial properties between an organic semiconductor and ${\alpha}$ metal electrode. The contact resistance is critical to the current flow in the device. The contact resistance arises mainly from the Schottky barrier formation due to the work function difference between the semiconductor and electrodes. We doped pentacene/source-drain interfaces with $F_4TCNQ$ (2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane), resulting in p-doped region at the SD contacts, in order to solve this problem. We found that the mobility increased and the threshold voltage decreased.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.12-18
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• 2008

Ag paste was employed for source and drain electrode of OTFTs and for the data metal lines of OTFT-OLED array on PC(polycarbonate) substrate. We tested two kinds of Ag-pastes such as pastes for 325 mesh and 500 mesh screen mask to examine the pattern ability and electrical performance for OTFTs. The minimum feature size was 60 ${\mu}m$ for 325 mesh screen mask and 40 ${\mu}m$ for 500 mesh screen mask. The conductivity was 60 $m{\Omega}/\square$ for 325 mesh and 133.1 $m{\Omega}/\square$ for 500 mesh. For the OTFT performance the mobility was 0.35 $cm^2/V{\cdot}sec$ and 0.12 $cm^2/V{\cdot}sec$, threshold voltage was -4.7 V and 0.9 V, respectively, and on/off current ratio was ${\sim}10^5$, for both screen masks. We applied the 500 mash Ag paste to OTFT-OLED array because of its good patterning property. The pixel was composed of two OTFTs and one capacitor and one OLED in the area of $2mm{\times}2mm$. The panel successfully worked in active mode operation even though there were a few bad pixels.