• Journal of Information Display
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• v.2 no.3
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• pp.72-77
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• 2001

Amorphous silicon thin-film transistors (a-Si TFTs) were incorporated into Mo-tip-based triode-type field emitters and diode-type ones of carbon nanotubes for an active-matrix cathode (AMC) plate of field emission displays. Also, we developed a novel surface-treatment process for the Mo-tip fabrication, which gleatly enhanced in the stability of field emission. The field emission currents of AMC plates on glass substrate were well controlled by the gate bias of a-Si TFTs. Active-matrix field emission displays (AMFEDs) with these AMC plates were demonstrated in a vacuum chamber, showing low-voltage matrix addressing, good stability and reliability of field emission, and highly uniform light emissions from the anode plate with phosphors. The optimum design of AMFEDs including a-Si TFTs and a new light shield/focusing grid is discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.483-485
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• 2007

The active-matrix field emission display (AMFED) was fabricated by integrating carbon nanotube emitters on a-Si thin-film transistors. Also, the tapered macro-gate was adopted for high immunity to a high anode voltage and strong electron beam focusing. The fabricated AMFED was successfully driven with a low voltage of below 15 V.

• ETRI Journal
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• v.24 no.4
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• pp.290-298
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• 2002

We present, for the first time, a prototype active-matrix field emission display (AMFED) in which an amorphous silicon thin-film transistor (a-Si TFT) and a molybdenum-tip field emitter array (Mo-tip FEA) were monolithically integrated on a glass substrate for a novel active-matrix cathode (AMC) plate. The fabricated AMFED showed good display images with a low-voltage scan and data signals irrespective of a high voltage for field emissions. We introduced a light shield layer of metal into our AMC to reduce the photo leakage and back channel currents of the a-Si TFT. We designed the light shield to act as a focusing grid to focus emitted electron beams from the AMC onto the corresponding anode pixel. The thin film depositions in the a-Si TFTs were performed at a high temperature of above 360°C to guarantee the vacuum packaging of the AMC and anode plates. We also developed a novel wet etching process for $n^+-doped$ a-Si etching with high etch selectivity to intrinsic a-Si and used it in the fabrication of an inverted stagger TFT with a very thin active layer. The developed a-Si TFTs performed well enough to be used as control devices for AMCs. The gate bias of the a-Si TFTs well controlled the field emission currents of the AMC plates. The AMFED with these AMC plates showed low-voltage matrix addressing, good stability and reliability of field emission, and good light emissions from the anode plate with phosphors.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.923-926
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• 2004

Active-matrix field emission display (AMFED) based on carbon nanotube (CNT) emitter and amorphous silicon thin-film transistor (a-Si TFT) is reviewed. The AMFED pixels consisted of a high-voltage a-Si TFT and mesh-gated CNT emitters. The developed AMFED panel showed a high performance with a driving voltage of below 15 V. The low-cost and large-area AMFED approach with a metal mesh technology will be discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.194-197
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• 2003

The actively addressable carbon nanotube (CNT) emitters have been studied for stable and low-voltage driving field emission display (FED). The a-Si TFT and screen-printed CNT emitters were successfully integrated to fabricate the diode type active-matrix cathode and FED panel. Also, we propose a new FED architecture based on the actively controlled triode CNT emitters showing the properties of ideal triode type cathode with electron beam focusing effect.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.33-37
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• 1999

We present, for the first time, a prototype active-matrix field emission display (AMFED) with 25$\times$25 pixels in which polycrystalline silicon fie이 emitter array (poly-Si FEA) and thin-film transistor (TFT) were monolityically intergrated on an insulating substrate. The FEAs showed relatively large electron emissions above at a gate voltage of 50 V, and the TFTs were designed to have low off-stage currents even though at high drain voltages. The intergrated poly-Si TFT controlled electron emissions of the poly-Si FEA actively, resulting in improvement in the emission stability and reliability along with a low-voltage control of field emission below 25V. With the prototype AMFED we have displayed character patterns by low-boltage pertipheral circuits of 15 V in a high vacuum chamber.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.141-145
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• 2006

The possibility of an active-matrix carbon nanotube field emission display (AM-CNT FED) is discussed from the view points of display performance and cost. The critical issues for FED commercialization such as anode acceleration voltage, uniformity, stability and reliability can be solved through our AM-CNT FED technologies.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.993-994
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• 2008

Electrochromic (EC) devices are capable of reversibly changing their optical properties upon charge injection and extraction induced by the external voltage. The characteristics of the EC device, such as low power consumption, high coloration efficiency, and memory effects under open circuit status, make them suitable for use in a variety of applications including smart windows and electronic papers. Coloration due to reduction or oxidation of redox chromophores can be used for EC devices (e-paper), but the switching time is slow (second level). Recently, with increasing demand for the low cost, lightweight flat panel display with paper-like readability (electronic paper), an EC display technology based on dye-modified $TiO_2$ nanoparticle electrode was developed. A well known organic dye molecule, viologen, was adsorbed on the surface of a mesoporous $TiO_2$ nanoparticle film to form the EC electrode. On the other hand, ZnO is a wide bandgap II-VI semiconductor which has been applied in many fields such as UV lasers, field effect transistors and transparent conductors. The bandgap of the bulk ZnO is about 3.37 eV, which is close to that of the $TiO_2$ (3.4 eV). As a traditional transparent conductor, ZnO has excellent electron transport properties, even in ZnO nanoparticle films. In the past few years, one-dimension (1D) nanostructures of ZnO have attracted extensive research interest. In particular, 1D ZnO nanowires renders much better electron transportation capability by providing a direct conduction path for electron transport and greatly reducing the number of grain boundaries. These unique advantages make ZnO nanowires a promising matrix electrode for EC dye molecule loading. ZnO nanowires grow vertically from the substrate and form a dense array (Fig. 1). The ZnO nanowires show regular hexagonal cross section and the average diameter of the ZnO nanowires is about 100 nm. The cross-section image of the ZnO nanowires array (Fig. 1) indicates that the length of the ZnO nanowires is about $6\;{\mu}m$. From one on/off cycle of the ZnO EC cell (Fig. 2). We can see that, the switching time of a ZnO nanowire electrode EC cell with an active area of $1\;{\times}\;1\;cm^2$ is 170 ms and 142 ms for coloration and bleaching, respectively. The coloration and bleaching time is faster compared to the $TiO_2$ mesoporous EC devices with both coloration and bleaching time of about 250 ms for a device with an active area of $2.5\;cm^2$. With further optimization, it is possible that the response time can reach ten(s) of millisecond, i.e. capable of displaying video. Fig. 3 shows a prototype with two different transmittance states. It can be seen that good contrast was obtained. The retention was at least a few hours for these prototypes. Being an oxide, ZnO is oxidation resistant, i.e. it is more durable for field emission cathode. ZnO nanotetropods were also applied to realize the first prototype triode field emission device, making use of scattered surface-conduction electrons for field emission (Fig. 4). The device has a high efficiency (field emitted electron to total electron ratio) of about 60%. With this high efficiency, we were able to fabricate some prototype displays (Fig. 5 showing some alphanumerical symbols). ZnO tetrapods have four legs, which guarantees that there is one leg always pointing upward, even using screen printing method to fabricate the cathode.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1111-1114
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• 2006

We have developed a 2 inch LTPS-TFT AMOLED display with a top emission structure on a $50-{\mu}m-thick$ metal foil. The Active matrix back planes were fabricated with the p-channel LTPS TFT with a conventional pixel circuit consisting of 2 transistors and 1 capacitance. The p-channel TFTs on the metal foil exhibited the field-effect mobility of $22cm^2/Vs$. Finally, a images from prototype monochrome AMOLED displays are successfully presented, with $64{\times}88$ pixels and 56-ppi resolution.