• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.63-67
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• 2005

Pentacene channel OTFT(organic thin film transistor)을 SiOC 절연박막 위에서 film by thermal evaporation 방법을 이용하여 성장시켰다. CVD 방법으로 증착시킨 SiOC 절연막은 조성비에 따라 특성이 달라지므로 절연막 위에서의 펜타센의 화학적 반응을 조사하기 위해서 inorganic-type인 $O_2/(BTMSM\;+\;O_2)$ = 0.5의 비율을 갖는 SiOC 박막을 사용하였다. 팬타센 분자의 말단에서 SiOC 표면에서 Diels-Alder 반응에 의한 이중결합이 깨어지면서 안정된 성장을 하지만 온도가 높아감에 따라 표면에서의 $SN_2$(bimolecular nucleophilic substitution) 반응과 연쇄적인 화학반응에 의해 팬타센의 성장을 방해하는 것으로 나타났다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.13-18
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• 2005

In this paper, we fabricated a pixel array in which each pixel was consisted of Organic Thin Film Transistor (OTFT) serially connected with Organic Light Emitting Diode (OLED) on Poly-ethylene-terephthalate (PET) substrate and the number of pixels was 64 x 64. As a gate insulator of OTFT, the thermally cross-linked PVP was used and the organic semiconductor, Pentacene, is deposited for an active layer of OTFT considering the compatibility with PET substrate. The mobility of OTFT is $1.0\;cm^2/V{\cdot}sec$ as a discrete device, but it was reduced to $0.1\~0.2\;cm^2/V{\codt}sec$ in the array. We analyzed the operation of the array and confirmed the current driving ability of OTFTs for the OLEDs.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.9-14
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• 2007

In this article, the organic integrated circuits such as inverter, ring oscillator, NAND and NOR gates, and rectifier have been fabricated on PEN substrate by using pentacene TFTs, The OTFTs used bottom contact structure and produced the average mobility of 0.26 $cm^2/V.sec$ and on/off current ratio of $10^5$. All circuits successfully worked as the simulation results. Especially, the rectifier was able to operate up to 1 MHz input AC signals, and ring oscillator exhibited oscillation frequency of 1MHz at 40 V. Based on the results of organic integrated circuits we could confirm the possibility of the low cost RFID tags and flexible display with OTFTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.202.2-202.2
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• 2015

현재 반도체 산업 전반에 걸쳐 사용되고 있는 실리콘등의 3차원 반도체 물질은 반도체 공정 기술의 발전에 따른 물질적인 한계에 부딪히고 있다. 이러한 물질적인 한계를 극복하기 위하여 Graphene과 같은 2차원 물질 중 전이금속 칼코게나이드 화합물(TMD)의 반도체 특성이 뛰어나 실리콘 등을 대체할 차세대 나노 반도체 물질로 활발한 연구가 이루어지고 있다. 특히 기존 반도체를 도핑시키기 위하여 사용되었던 이온 주입 공정은 TMD의 결정구조에 심각한 손상을 가하여 이를 대체할 새로운 도핑 방법에 대한 연구가 활발히 이루어지고 있다. 우리는 이번 연구에서 기존에 유기반도체 물질로 연구되었던 pentacene을 도핑층으로 활용하고 Raman 분광법 및 전기 측정 등을 통하여 TMD물질이 금속화 되지 않는 정도의 매우 낮은 p형 도핑 현상을 확인하였다. 또한 시간에 따른 측정을 통하여 pentacene의 p형 도핑현상이 필름 증착 직후에는 미약하지만 시간이 지나면서 점점 강해지는 것을 발견하였다.. 이는 도핑현상이 pentacene의 구조에 의해 주로 일어나는 것으로 시간이 지남에 따라 대기중의 수분에 의해 생성된 pentacene 산화물들이 도핑 현상을 증가 시키는 원인으로 보인다.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.441-445
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• 2007

In this paper we demonstrated the applications of OTFTs (organic thin film transistors) to flexible displays such as AM-EPD (active matrix electrophoretic display) and AM-OLED (active matrix organic light emitting diode), and also to integrated circuits. The OTFTs using pentacene semiconductor layer and PVP gate dielectric and Au S/D electrodes exhibited good performance for AM-EPD with the mobility of $0.59\;cm^{2}/V.sec,$ and with also good uniformity over 2.5" diagonal area. However, it is nor enough for AM-OLED requiring the mobility larger than $1\;cm^{2}/V.sec$ for large area displays. The integrated circuits also worked, producing the operating frequency of 1MHz. We need to develop a fabrication process to reduce parasitic capacitance for high frequency operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.76-76
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• 2010

유기박막트랜지스터의 특성을 개선하기 위해서는 유기반도체와의 좋은 접합과 유전상수가 주요한 요인으로 작용한다. 무기 산화물 전구체와 유기고분자를 이용하여 유기 고분자의 단정인 낮은 유전율을 개선하였다. 스핀코팅 방법이 아닌 딥코팅 방법을 이용하여 절연막 두께를 10nm정도로 낮추어 구동전압을 개선하였으며 무기 절연체의 높은 누설전류 또한 그 특성이 개선되어 우수한 절연 특성을 보였다. 유-무기 복합체를 이용한 게이트 절연막과 펜타센을 이용한 유기박막트랜지스터의 구동전압은 1V정도에서 구동가능하며, 점멸비, 이동도 모두 개선된 결과를 보였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.500-505
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• 2012

In this study, the influence of the intermolecular distance on the charge mobility in a pentacene thin-film was investigated. In order to increase the mobility which depends on the ${\pi}$-overlap between molecules, the intermolecular distance was shortened by compressive force along the conduction channel. Pentacene thin-film was fabricated on flexible substrates bent outward at different radii to stretch the gate dielectric surface and then the substrates were unbent, producing the compressive force to the film. The result showed that the mobility increased proportionally to the strain applied during the pentacene deposition and the molecular packing inside a grain was not optimal for the charge transport.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.512-518
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• 2006

In this paper, we investigated the deposition of pentacene thin film on a large area substrate by Organic Vapor Phase Deposition(OVPD) and applied it to fabrication of Organic Thin Film Transistor(OTFT). We extracted the optimum deposition conditions such as evaporation temperature of $260^{\circ}C$, carrier gas flow rate of 10 sccm and chamber vacuum pressure of 0.1 torr. We fabricated 72 OTFTs on the 4 inch size Si Wafer, Which produced the average mobility of $0.1{\pm}0.021cm^2/V{\cdot}s$, average subthreshold slope of 1.04 dec/V, average threshold voltage of -6.55 V, and off-state current is $0.973pA/{\mu}m$. The overall performance of pentacene TFTs over 4 ' wafer exhibited the uniformity with the variation less than 20 %. This proves that OVPD is a suitable methode for the deposition of organic thin film over a large area substrate.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.551-554
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• 2011

One of the key issues in the research of organic field-effect transistors (OFETs) is the low-voltage operation. To address this issue, we synthesized poly(styrene-r-benzocyclobutene-r-methyl methacrylate) (P(S-r-BCB-r-MMA)) as a thermally cross-linkable gate dielectrics. The P(S-r-BCB-r-MMA) showed high quality dielectric properties due to the negligible volume change during the cross-linking. The pentacene FETs based on the 34 nm-thick P(S-r-BCB-r-MMA) gate dielectrics operate below 5 V. The P(S-r-BCB-r-MMA) gate dielectrics yielded high device performance, i.e. a field-effect mobility of $0.25cm^2/Vs$, a threshold voltage of -2 V, an sub-threshold slope of 400 mV/decade, and an on/off current ratio of ${\sim}10^5$. The thermally cross-linkable P(S-r-BCB-r-MMA) will provide an attractive candidate for solution-processable gate dielectrics for low-voltage OFETs.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.375-378
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• 2004

In this paper, we fabricated pantacene TFTs using PVP copolymer and cross-linked PVP as gate insulator on glass and plastic (PET) substrate. Depending on the density of PVP and poly (melamine-co-formaldehyde) the performance has been changed. We obtained the best performance with the mobility of 0.12cm2/V sec and the on/off current ratio of $1.19{\times}10^6$ for the case of $10wt\%$ PVP copolymer mixed with $5wt\%$ poly(melamine-co-formaldehyde). Additionally using OTFTs with the above PVP gate insulator, we fabricated the integrated circuit including inverter which produced the gain of 5.56 on the glass substrate and gain of 9.7 on the plastic (PET) substrate. And the threshold voltage was respectively +8V and +14v$ldots$