• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.203-203
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• 2009

Low temperature annealing for oxide TFTs including IGZO on PI substrate is the essential process to fabricate flexible display devices, since low heat-resistance on PI and PEN substrates limits the temperature range. Laser annealing is one of the promising candidates for low temperature process, and it has been used for various application in semiconductor and LCD fabrication. We irradiated laser to solution-based IGZO thin films on PI substrate were irradiated to laser beam, and investigated laser damage of PI layer. Based on transmittance analysis, wavelength(532nm) and scan speed(1000mm/s) is the optimized condition for laser irradiation about ink-Jet printed oxide TFTs on PI substrates.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.93-93
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• 2011

The Indium Zinc Tin Oxide (IZTO) and Indium Tin Oxide (ITO) thin films are grown on PI substrate at different substrate temperature by pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt.%, ZnO 15 wt.%, SnO2 15 wt.%) and ITO (In2O3 90wt.%, SnO2 10wt.%). The structural, electrical, and optical properties are investigated. The IZTO thin films deposited at low temperature showed relatively low electrical resistivity compared to ITO thin films deposited at low temperature. As a result, we could prepare the IZTO thin films with the resistivity as low as $5.6{\times}10^{-4}({\Omega}{\cdot}m)$. Both of the films deposited on PI substrate showed an average transmittance over 80% in visible range (400.800nm). Overall, IZTO thin film is a promising candidate as an alternative TCO material to ITO in flexible and OLED devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.866-870
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• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles on thin plastic substrates generated higher than that on glass substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer substrate are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on g1ass.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04a
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• pp.18-22
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• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using thin plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles generated are about $3^{\circ}$ by the rubbing alignment method on thin plastic substrates, However, the pretilt angle are at about $1.7^{\circ}$ lower on the glass substrate than on thin plastic substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on glass.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.171-177
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• 2001

The adhesion enhancement from inserting a RF bias-sputtered Cr layer between Cu and polyimide (PI) has been studied. The RF bias power applied in this study was ranged from 0 to 400 W. Without the RF bias, the peel strength, which measures the adhesion strength, was nearly o g/mm. As the RF power was increased, the peel strength rose up to ~130 g/mm at 200 W, which remained constant with further increase of the RF bias power. Cross-sectional transmission electron microscopy(TEM) was used to investigate the interfacial reaction between the Cr film and PI substrate during the bias sputtering. The Cr/PI interface without the application of RF dais showed a clean, sharp interface while the RF raised Cr/PI interface had about 10~30 nm thick atomistically mixed interlayer between the metal film and PI substrate. This interlayer appeared to have resulted from the implantation of high energy adatoms during the RF bias sputtering of Cr film. This mixed layer serves as an interlocking layer, which enhances adhesion between the metal and PI layers.

• Electronic Materials Letters
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• v.14 no.6
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• pp.749-754
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• 2018

Previous studies have reported on the mechanical robustness and chemical stability of flexible amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) on plastic substrates both in flat and curved states. In this study, we investigate how the polyimide (PI) substrate affects hydrogen concentration in the a-IGZO layer, which subsequently influences the device performance and stability under bias-temperature-stress. Hydrogen increases the carrier concentration in the active layer, but it also electrically deactivates intrinsic defects depending on its concentration. The influence of hydrogen varies between the TFTs fabricated on a glass substrate to those on a PI substrate. Hydrogen concentration is 5% lower in devices on a PI substrate after annealing, which increases the hysteresis characteristics from 0.22 to 0.55 V and also the threshold voltage shift under positive bias temperature stress by 2 ${\times}$ compared to the devices on a glass substrate. Hence, the analysis and control of hydrogen flux is crucial to maintaining good device performance and stability of a-IGZO TFTs.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.390-394
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• 2019

This paper presents an inkjet-printed plastic force sensor using PEDOT:PSS. Using a piezoelectric-type inkjet printer, the force sensor was manufactured by printing PEDOT:PSS ink onto a polyimide (PI) substrate film. Applying a vertical force of 0 to 100 N to the force sensor on the PI substrate with a thickness of 64 mm, the resistance of the force sensor increased in proportion to the input force by the length deformation of the PI substrates and the sensor pattern. As a result, the fabricated sensor has a characteristic of 0.001% /N with a linearity of 99.38%. In addition, as the thickness of the PI substrate film increased, the sensitivity of the sensor increased linearly. The fabricated force sensor is expected to be applied to industrial sites and healthcare fields.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.4
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• pp.307-311
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• 2017

Ultra short pulse laser processing with the PI (polyimide) substrate is conducted to increase flexibility and radius of curvatures. A femtosecond laser is used to perform micro machining by minimizing the heat effect in PI substrate. The laser processing according to the parameters, such as fabricated line width, depth, laser power, distance between lines, is carried out to understand the characteristics of fabricated lines. A bending test is carried out to evaluate bending shapes and the radius of curvature after bending and spreading it 1000 times. The results demonstrates that the radius of curvature decreases in deepen lines and increases with the augment of the number of the fabricated lines, and distance between lines.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1125-1131
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• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on the two kinds of polyimide (PI) surfaces using thin plastic substrates. The NLC pretilt angles generated on thin plastic substrates are higher than that on the glass substrate. We study that AFM (atomic force microscope) image of rubbed PI surface with polymer film has formed the micro-groove. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.162-163
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• 2006

Control over surface induced self-assembly of electronically active pi-conjugated molecules provides great opportunities to fine-tune and optimize their electrical properties in organic electronics. In this study, with the aim of enhancing the electrical performances by promoting surface induced two-dimensional self-assembly in representative pi-conjugated molecules such as poly (3-hexylthiophene) and pentacene, we have controlled the intermolecular interaction at the interface between pi-conjugated molecules and substrate by using self-assembled monolayers functionalized with various groups. We will discuss the dependency of pi-conjugated molecules on the specific properties of the substrate surface and the effect of surface induced self-assembly on electrical performances in organic transistors.