• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.431-431
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• 2013

Flexible Organic Light Emitting Diode (OLED) displays are required for future devices. It is possible that plastic substrates are instead of glass substrates. But the plastic substrates are permeable to moisture and oxygen. This weak point can cause the degradation of fabricated flexible devices; therefore, encapsulation process for flexible substrate is needed to protect organic devices from moisture and oxygen. Y.G. Lee et al.(2009) [1] reported organic and inorganic multilayer structure as an encapsulation barrier for enhanced reliability and life-time.Flowable Oxide process is a low-temperature process which shows the excellent gap-fill characteristics and high deposition rate. Besides, planarization is expected by covering dust smoothly on the substrate surface. So, in this research, Bi-layer structured is used for encapsulation: Flowable Oxide Thin film by PECVD process and Al2O3 thin film by ALD process. The samples were analyzed by water vapor transmission rate (WVTR) using the Calcium test and film cross section images were obtained by FE-SEM.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.452-455
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• 2007

This paper provides an overview on the characteristics of a-SiC:H barrier film deposited for flexible display applications. Key characteristics such as high crack resistance, high thermal/hydro stability, excellent adhesion to the polymer substrate, as well as very low permeance has been demonstrated. The excellence of this barrier film has been shown from competitive analysis compared with other barrier coating materials. Finally, flexible Polymer Light Emitting Diode (PLED) test pixels have been fabricated on the barrier coated plastic substrate, demonstrating the viability of the device with lifetime data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.115-116
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• 2012

The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.87-96
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• 2019

유기 박막 트랜지스터 (OTFT) 백플레인을 이용한 유연한 유기 발광 다이오드 (OLED) 디스플레이가 연구되고 있다. OLED 디스플레이의 구동을 위해서 게이트 드라이버가 필요하다. 저온, 저비용 및 대 면적 인쇄 프로세스를 사용하는 디스플레이 패널의 내장형 게이트 드라이버는 제조비용을 줄이고 모듈 구조를 단순화한다. 이 논문에서는 유연한 OLED 디스플레이 패널의 내장형 게이트 드라이버 제작을 위하여 OTFT를 사용한 의사 CMOS (pseudo complementary metal oxide semiconductor) 로직 게이트를 구현한다. 잉크젯 인쇄형 OTFT 및 디스플레이와 동일한 프로세스를 사용하여 유연한 플라스틱 기판 상에 의사 CMOS 로직 게이트가 설계 및 제작되며, 논리 게이트의 동작은 측정 실험에 의해 확인된다. 최대 1 kHz의 입력 신호 주파수에서 의사 CMOS 인버터의 동작 결과를 통하여 내장형 게이트 드라이버의 구현 가능성을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.141-144
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• 2004

A QVGA active-matrix backplane is produced on a 25${\mu}m$ thin plastic substrate. A 4-mask photolithographic process is used. The insulator layer and the semiconductor layer are organic material processed from solution. This backplane is combined with the electrophoretic display effect supplied by SiPix and E ink, resulting in an electronic paper display with a thickness of only 100${\mu}m$. This is world's thinnest active-matrix display ever made.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.746-748
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• 2004

a-Si TFTs with field-effect mobility of 1.2 $cm^2$/V-s have been fabricated on plastic substrate. Pixel circuits on plastic for AMOLED were made with the same low-temperature fabrication process. The circuits compensate for $V_T$-shift, exhibit high output current, retain functionality and drive current level during long-time continuous operation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.198.1-198.1
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• 2016

Organic light-emitting diode (OLED) displays have promising potential to replace liquid crystal displays (LCDs) due to their advantages of low power consumption, fast response time, broad viewing angle and flexibility. Organic light emitting materials are vulnerable to moisture and oxygen, so inorganic thin films are required for barrier substrates and encapsulations.[1-2]. In this work, the silicon-based inorganic thin films are deposited on plastic substrates by plasma-enhanced chemical vapor deposition (PECVD) at low temperature. It is necessary to deposit thin film at low temperature. Because the heat gives damage to flexible plastic substrates. As one of the transparent diffusion barrier materials, silicon oxides have been investigated. $SiO_x$ have less toxic, so it is one of the more widely examined materials as a diffusion barrier in addition to the dielectric materials in solid-state electronics [3-4]. The $SiO_x$ thin films are deposited by a PECVD process in low temperature below $100^{\circ}C$. Water vapor transmission rate (WVTR) was determined by a calcium resistance test, and the rate less than $10.^{-2}g/m^2{\cdot}day$ was achieved. And then, flexibility of the film was also evaluated.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.251-254
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• 2007

Principal challenges to $\underline{direct\;fabrication}$ of high performance a-Si:H transistor arrays on flexible substrates include automated handling through bonding-debonding processes, substrate-compatible low temperature fabrication processes, management of dimensional instability of plastic substrates, and planarization and management of CTE mismatch for stainless steel foils. Viable solutions to address these challenges are described.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.44-44
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• 2009

Recently, transparent ZnO-based TFTs have attracted much attention for flexible displays because they can be fabricated on plastic substrates at low temperature. We report the fabrication and characteristics of ZnO channel layers(ZnO TFTs) having different channel thicknesses. The ZnO film were deposited as active channel layers on $Si_3N_4/Ti/SiO_2p$-Si substrates by rf magnetron sputtering at $100\;^{\circ}C$ without additional annealing. Also the Zno thin films deposited at oxygen partial pressures of 40%. ZnO TFTs using a bottom-gate configuration were investigated. The $Si_3N_4$ film were deposited as gate insulator by PE-CVD at $15\;^{\circ}C$. All Processes were processed below $150^{\circ}C$ which is optimal temperature for flexible display and were used dry etching method.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.431-433
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• 2009

We developed 4.8 inch WQVGA e-paper on plastic substrate using organic field effect transistors (OFETs). Polyethylene naphthalate (PEN) film was used as a flexible substrate and arrays of OFETs with bottom-gate, bottom-contact structure were fabricated on it. Lowtemperature curable organic gate insulating materials were employed and polymer semiconductor solutions were ink-jetted on arrays with high-resolution. At all steps, process temperature was limited below $130^{\circ}C$. Finally, we could drive flexible e-paper displays based on OFET arrays with the resolution of 100 dpi.