• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1459-1462
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• 2008

In this paper we describe solutions to address critical challenges in direct fabrication of amorphous silicon thin film transistor (TFTs) arrays for active matrix flexible displays. For all flexible substrates a manufacturable handling protocol in automated display-scale equipment is required. For metal foil substrates the principal challenges are planarization and electrical isolation, and management of stress (CTE mismatch) during TFT fabrication. For plastic substrates the principal challenge is dimensional instability management.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1364-1366
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• 1998

An active-matrix LCD using thin film transistors (TFT) has been widely recognized as having potential for high-quality color flat-panel displays. Pixel-Design Array Simulation Tool (PDAST) was used to profoundly understand the gate signal distortion and pixel charging capability, which are the most critical limiting factors for high-quality TFT-LCDs. Since PDAST can simulate the gate, data and pixel voltages of a certain pixel on TFT array at any time and at any location on an array, the effect of the resistivity of gate line material on the pixel operations can be effectively analyzed. The gate signal delay. pixel charging ratio, level-shift of the pixel voltage were simulated with varying the parameters. The information obtained from this study could be utilized to design the larger area and finer image quality panel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1125-1128
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• 2002

Tantalum pentoxide (Ta$_2$O$\sub$5/) is a candidate for use in metal-insulator-metal diode in switching devices for active-matrix liquid-crystal displays. The MIM diode with very low threshold voltage and perfect symmetry was fabricated. High quality Ta$_2$O$\sub$5/ thin films were obtained by using an anodizing method. Rutherford backscattering spectroscopy, transmission electron microscope observations, auger electron spectroscopy, ellipsometry measurements, and electrical measurements, such as current - voltage(I-V) measurements were performed to investigate Ta$_2$O$\sub$5/ films and their reliability and indicated that the obtained TaOx thin films were reliable Ta$_2$O$\sub$5/ films for the applications. Furthermore, in this paper, we discuss the effects of top-electrode metals and annealing conditions. The conduction mechanism of the leakage current and the symmetry characteristics related to the Schottky emission and Poole-Frankel effect are also discussed using the results of electrical measurements and conduction barrier theory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1582-1584
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• 1996

The polycrystalline silicon thin film transistors (poly-Si TFT) are the most promising candidate for active matrix liquid crystal displays (AMLCD) for their high mobilities and current driving capabilities. The leakage current of the poly-Si TFT is much higher than that of the amorphous-Si TFT, thus larger storage capacitance is required which reduces the aperture ratio fur the pixel. The offset gated poly-Si TFTs have been widely investigated in order to reduce the leakage current. The conventional method for fabricating an offset device may require additional mask and photolithography process step, which is inapplicable for self-aligned source/drain ion implantation and rather cost inefficient. Due to mis-alignment, offset devices show asymmetric transfer characteristics as the source and drain are switched. We have proposed and fabricated a new offset poly-Si TFT by applying photoresist reflow process. The new method does not require an additional mask step and self-aligned ion implantation is applied, thus precise offset length can be defined and source/drain symmetric transfer characteristics are achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.957-960
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• 2009

Sensor applications of thin-film transistors (TFTs), such as photosensor, magnetic sensor, temperature sensor and chemical sensor, are introduced. Active-matrix circuits and amplifying circuits using poly-Si TFTs are integrated with these sensors to improve sensor performances and generate additional functions. These sensors may be promising applications after flat-panel displays (FPDs) in giant-micro electronics.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.448-451
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• 2007

DuPont Teijin $Films^{TM}$ (DTF) have developed engineered substrates specifically for the flexible electronics market. $Teonex^{(R)}$ Q65, $Melinex^{(R)}$ ST506 and ST504 are biaxially oriented crystalline polyesters with the option of planarised surfaces. These films are emerging as competitive materials for the base substrate in OLED displays and active matrix backplanes. Given the demanding dimensional reproducibility requirements in the display applications, it is critical to control the several factors that can influence the film distortion in order to achieve the ultimate performance. This paper will discuss the impact of thermal stress, mechanical stress and the processing environment on dimensional reproducibility of polyester film and give examples of how this impacts on the film in device manufacture.

• 한국산학기술학회논문지
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• 제8권4호
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• pp.738-742
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• 2007

능동형 평판디스플레이 소자를 제작하기 위해 수소화된 비정질 규소 박막트랜지스터 (a-Si:H TFT)의 상부에 화소전극을 형성하는 과정에 따른 TFT의 특성 변화를 연구하였다. 화소전극 형성 전에 1 pA 수준의 오프상태 전류 및 $10^6$ 이상의 스위칭률을 보이던 TFT에 화소전극 공정을 행하면 오프상태 전류가 10 pA 이상으로 증가하여 소자특성이 악화되었다. 이러한 소자특성의 악화는 SiNx 보호막 표면의 플라즈마 처리로 개선될 수 있었는데, 특히 $N_2$ 플라즈마가 좋은 결과를 보였다. 화소전극 공정에 의해서 누설전류가 증가하는 것은 투명전도막 증착공정 중에 SiNx 보호막 표면에 전하가 축적되어 이에 유도되는 백채널의 캐리어 축적에 기인하는 것으로 추정된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.76.1-76.1
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• 2013

Atomic Layer Deposition (ALD) has remarkably developed in semiconductor and nano-structure applications since early 1990. Now, the advantages of ALD process are well-known as controlling atomic-level-thickness, manipulating atomic-level-composition control, and depositing impurity-free films uniformly. These unique properties may accelerate ALD related industries and applications in various functional thin film markets. On the other hand, one of big markets, Display industry, just starts to look at the potential to adopt ALD functional films in emerging display applications, such as transparent and flexible displays. Unlike conventional ALD process strategies (good quality films and stable precursors at high deposition processes), recently major display industries have suggested the following requirements: large area equipment, reasonable throughput, low temperature process, and cost-effective functional precursors. In this talk, it will be mentioned some demands of display industries for applying ALD processes and/or functional films, in terms of emerging display technologies. In fact, the AMOLED (active matrix organic light emitting diode) Television markets are just starting at early 2013. There are a few possibilities and needs to be developing for AMOLED, Flexible and transparent Display markets. Moreover, some basic results will be shown to specify ALD display applications, including transparent conduction oxide, oxide semiconductor, passivation and barrier films.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.50-55
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• 2022

Due to the wavelength shift problem of micro LED caused by the change of current density, the active matrix driving pixel circuit that is used in OLED cannot be applied to micro LED displays. Therefore, we need a gray scale method based on modulation of duration time of light emission. In this study, we propose the PWM-controlled micro LED pixel circuit based on CMOS thin film transistors (TFTs). By adopting CMOS inverter structure, we can reduce the number of storage capacitors from the circuit and make the operating speed of the circuit faster. Most of all, our circuit is designed to make operating speed of PWM circuit faster by adopting feedback effect through double gate TFT structure. As a result, it takes about 4.7ns to turn on the LED and about 5.6ns to turn it off. This operating time is short enough to avoid the color distortion and help the precise control of the gray scale.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권4호
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• pp.161-168
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• 2001

Organic thin film transitors(TFTs) are of interest for use in broad area electronic applications. For example, in active matrix liquid crystal displays(AMLCDs), organic TFTs would allow the use of inexpensive, light-weight, flexible, and mechanically rugged plastic substrates as an alternative to the glass substrates needed for commonly used hydrogenated amorphous silicon(a-Si:H). Recently pentacene TFTs with carrier field effect, mobility as large as 2 $cm^2V^{-1}s^{-1}$ have been reported for TFTs fabricated on silicon substrates, and it is higher than that of a-Si:H. But these TFTs are fabricated on silicon wafer and $SiO_2$ was used as a gate insulator. $SiO_2$ deposition process requires a high insulator which is polyimide and photo acryl. We investigated trasfer and output characteristics of the thin film transistors having active layer of pentacene. We calculated field effect mobility and on/off ratio from transfer characteristics of pentacene thin film transistor, and measured IR absorption spectrum of polymide used as the gate dielectric layer. It was found that using the photo acryl as a gate insulator, threshold voltage decreased from -12.5 V to -7 V, field effect mobility increased from 0.012 $cm^2V^{-1}s^{-1}$ to 0.039 $cm^2V^{-1}s^{-1}$ , and on/off current ratio increased from $10^5\;to\;10^6$. It seems that TFTs using photo acryl gate insulator is apt to form channel than TFTs using polyimide gate insulator.