• 마이크로전자및패키징학회지
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• 제16권4호
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• pp.17-22
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• 2009

Two different organic-inorganic hybrid thin film transistors (OITFTs) with the structures of glass/ITO/ZnO/PMMA/Al (staggered structure) and glass/ITO/PMMA/ZnO/Al (inverted staggered structure), were fabricated and their electrical and structural properties were compared. The ZnO thin films used as active channel layers were deposited by the atomic layer deposition (ALD) method at a temperature of $100^{\circ}C$. To investigate the effect of the substrates on their properties, the ZnO films were deposited on bare glass, PMMA/glass and ITO/glass substrates and their crystal properties and surface morphologies were analyzed. The structural properties of the ZnO films varied with the substrate conditions. The ZnO film deposited on the ITO/glass substrate showed better crystallinity and morphologies, such as a higher preferred c-axis orientation, lower FWHM value and larger particle size compared with the one deposited on the PMMA/glass substrate. The field effect mobility ($\mu$), threshold voltage ($V_T$) and $I_{on/off}$ switching ratio for the OITFT with the staggered structure were about $0.61\;cm^2/V{\cdot}s$, 5.5 V and $10^2$, whereas those of the OITFT with the inverted staggered structure were found to be $0.31\;cm^2/V{\cdot}s$, 6.8 V and 10, respectively. The improved electrical properties for the staggered OITFTs may originate from the improved crystal properties and larger particle size of the ZnO active layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.395-395
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• 2007

We report on the fabrication of soluble pentacene-based thin-film transistors (TFTs) that consist of $NiO_x$, poly-vinyl phenol (PVP), and Ni for the source-drain (SID) electrodes, gate dielectric, and gate electrode, respectively. The $NiO_x$ SID electrodes of which the work function is well matched to that of soluble pentacene are deposited on a soluble pentacenechannel by sputter deposited of NiO powder and show a moderately low but still effective transmittance of ~65% in the visible range along with a good sheet resistance of ${\sim}40{\Omega}/{\square}$. The maximum saturation current of our soluble pentacene-based TFT is about $15{\mu}A$ at a gate bias of -40showing a high field effect mobility of $0.06cm^2/Vs$ in the dark, and the on/off current ratio of our TFT is about $10^4$. It is concluded that jointly adopting $NiO_x$ for the S/D electrodes and PVP for gate dielectric realizes a high-quality soluble pentacene-based TFT.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1653-1658
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• 2012

A new anthracene-containing conjugated molecule was synthesized through the Sonogashira coupling and reduction reactions. 1-Ethynyl-4-hexylbenzene was coupled to 2,6-bis((4-hexylphenyl) ethynyl)anthracene-9,10-dione through a reduction reaction to generate 2,6,9,10-tetrakis((4-hexylphenyl)ethynyl) anthracene. The semiconducting properties were evaluated in an organic thin film transistor (OTFT) and a single-crystal field-effect transistor (SC-FET). The OTFT showed a mobility of around 0.13 $cm^2\;V^{-1}\;s^{-1}$ ($I_{ON}/I_{OFF}$ > $10^6$), whereas the SC-FET showed a mobility of 1.00-1.35 $cm^2\;V^{-1}\;s^{-1}$, which is much higher than that of the OTFT. Owing to the high photoluminescence quantum yield of 2,6,9,10-tetrakis((4-hexylphenyl)ethynyl) anthracene, we could observe a significant increase in drain current under irradiation with visible light (${\lambda}$ = 538 nm, 12.5 ${\mu}W/cm^2$).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1292-1294
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• 2007

In this report, the effects of chemical surface treatments of ITO gate electrodes of OTFTs have been studied by using acid and base solutions. As a result, it is observed that the threshold voltage of OTFTs could be influenced and modified by the surface treatments. The device with an ITO gate electrode surface-treated by a base solution shows the lowest threshold voltage of -7.66 V, while the threshold voltages are about -13.51 V and -15.3 V for the devices without a surface treatment and with the acid solution treatment, respectively. It is thought that the work function of ITO electrode surface might be affected by the surface treatments, thereby influencing the threshold voltage.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.45-48
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• 2002

Poly(3-hexylthiophene) or P3HT based organic thin film transistor (OTFT) array was fabricated on flexible poly carbonate substrates and the electrical characteristics were investigated. As the gate dielectric, a dual layer structure of polyimide-$SiO_2$ was used to improve the roughness of $SiO_2$ surface and further enhancing the device performance and also source-drain electrodes were $O_2$ plasma treated for improvement of the electrical properties, such as drain current and field effect mobility. For the active layer, polymer semiconductor, P3HT layer was printed by contact-printing and spin-coating method. The electrical properties of OTFT devices printed by both methods were evaluated for the comparison. Based on the experiments, P3HT-based OTFT array with field effect mobility of 0.02~0.025 $cm^{2}/V{\cdot}s$ and current modulation (or $I_{on}/I_{off}$ ratio) of $10^{3}\sim10^{4}$ was fabricated.

• 대한전자공학회논문지SD
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• 제46권8호
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• pp.1-5
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• 2009

본 논문에서는 저전압에서 다결정 실리콘(Polycrysta1line Silicon: Poly-Si) 박막 트랜지스터 (Thin Film Transistors: TFTs) 의 문턱전압(threshold voltage)의 불균일성을 보상한 새로운 AMOLEDs(Active Matrix Organic Light Diodes) 구동 회로를 제안한다, 제안한 회로는 6개의 스위칭, 1개의 드라이빙 TFT와 1개의 저장 콘덴서로 구성되어 있으며, SPICE 시뮬레이션을 통해 구동회로의 동작을 검증하였다. 시뮬레이션 결과 5V정도의 낮은 구동 전압($V_{DD}$)에서 제안한 화소 구동회로의 OLED 출력 전류는 0.8%정도의 오차를 갖는 반면 기본적인 구동회로의 경우 약20%정도의 오차를 갖는 것을 확인할 수 있었다. 본 논문에서 제안한 화소 구동회로는 OLED의 전류를 결정하는 driving TFT의 threshold voltage 변화에 따른 전류의 변화를 성공적으로 보상하였고, 안정화된 전류를 OLED를 흘려주어 기본적인 화소 회로가 가지고 있던 불균일화의 문제를 해결함을 알 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1313-1314
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• 2007

This paper presents organic thin-film transistors (OTFTs) with poly(3-hexylthiophene)(P3HT) semiconductor and several polymeric dielectric materials of poly(vinyl phenol)(PVP), poly(vinyl alcohol)(PVA), and polyimide(PI) by using soluble process. The fabricated OTFT's have inverted staggered structure using transmission line method(TLM) pattern. In order to evaluate the electrical characteristics of the OTFT, capacitance-voltage(C-V) and current-voltage(I-V) were measured. C-V graphs were measured at several frequencies of 100 Hz, 1 kHz, and 1 MHz and ID-VDS graphs according to $V_{GS}$. The current on/off ratio and threshold voltage with each of PVP, PVA, and PI based OTFTs were measured to $10^3$, and -0.36, -0.41, and -0.62 V. Also, the calculated mobility with each of PVP, PVA, and PI was 0.097, 0.095, and 0.028 $cm^{2}V^{-1}s^{-1}$, respectively. In the cases of PVP and PVA, the hole mobility of P3HT was in excellent agreement with the published value of 0.1 $cm^{2}V^{-1}s^{-1}$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1220-1224
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• 2007

The effects of plasma damages to the organic thin film transistor (OTFT) during the fabrication process are investigated; metal deposition process on the organic gate insulator by plasma sputtering mainly generates the process induced damages of bottom contact structured OTFTs. For this study, various deposition methods (thermal evaporation, plasma sputtering, and neutral beam based sputtering) and metals (gold and Indium-Tin Oxide) have been tested for their damage effects onto the Poly 4-vinylphenol(PVP) layer surface as an organic gate insulator. The surface damages are estimated by measuring surface energies and grain shapes of organic semiconductor on the gate insulator. Unlike thermal evaporation and neutral beam based sputtering, conventional plasma sputtering process induces serious damages onto the organic surface as increasing surface energy, decreasing grain sizes, and degrading TFT performance.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.278.1-278.1
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• 2014

Organic materials have been explored as the gate dielectric layers in thin film transistors (TFTs) of backplane devices for flexible display because of their inherent mechanical flexibility. However, those materials possess some disadvantages like low dielectric constant and thermal resistance, which might lead to high power consumption and instability. On the other hand, inorganic gate dielectrics show high dielectric constant despite their brittle property. In order to maintain advantages of both materials, it is essential to develop the alternative materials. In this work, we manufactured nanocomposite gate dielectrics composed of organic material and inorganic nanoparticle and integrated them into organic TFTs. For synthesis of nanocomposite gate dielectrics, polyimide (PI) was explored as the organic materials due to its superior thermal stability. Candidate nanoprticles (NPs) of halfnium oxide, titanium oxide and aluminium oxide were considered. In order to realize NP concentration dependent electrical characteristics, furthermore, we have synthesized the different types of nanocomposite gate dielectrics with varying ratio of each inorganic NPs. To analyze gate dielectric properties like the capacitance, metal-Insulator-metal (MIM) structures were prepared together with organic TFTs. The output and transfer characteristics of organic TFTs were monitored by using the semiconductor parameter analyzer (HP4145B), and capacitance and leakage current of MIM structures were measured by the LCR meter (B1500, Agilent). Effects of mechanical cyclic bending of 200,000 times and thermally heating at $400^{\circ}C$ for 1 hour were investigated to analyze mechanical and thermal stability of nanocomposite gate dielectrics. The results will be discussed in detail.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.323-324
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• 2009

We investigated the electrical properties of tris-isopropylsilylethynyl (TIPS)-pentacene organic thin-film transistors (OTFTs) employing Ni/Ag source/drain electrodes. The gap height between the gate insulator and S/D electrode was controlled by changing the thickness of Ag under-layer(20, 30, 40 and 50nm). After evaporating the Ni under-layer, TIPS pentacene channel material was dropping the gap between the gate insulator and SID electrodes. The electrical proprieties of OTFT such as filed-effect mobility, on/off ratio, threshold voltage and subthreshold slope were significantly influenced by the gap height.