63.3: Active-Matrix Cathodes with Tapered Macro-Gate for High-Performance Field Emission Display

Abstract

A color field emission display was developed with active-matrix cathodes and tapered macro-gate (TMG). The cascade-connected a-Si TFTs exhibited well controlled field emissions from carbon nanotube (CNT) emitters. The TMG protected the CNT emitters from the anode field perfectly, enabling us to apply a high anode voltage over 10 kV. IntroductionSince the first application of carbon nanotube (CNT) as an electron source, there were many attempts to make CNT-field emission display (FED) [1][2][3][4]. To construct uniform and reliable CNT emitters is one of the critical issues. Furthermore, a very high anode-accelerating voltage is essential in FED to guarantee commercial brightness, lifetime and efficiency in the absence of low voltage phosphors. The commercially available phosphors need very high energy electrons above 7 KeV, which in turn requires high anode voltage architecture in FED.We proposed that an active-matrix (AM) cathode with thin-film transistor (TFT) could be a good choice for FED, and demonstrated mono AM-FEDs [5][6][7]. Also, the mesh gate structure along with the AM cathode of a-Si TFTs and CNT emitters was proposed [6][7], and here we renamed it the tapered macro-gate (TMG) to clarify its function compared with general mesh structure. The TMG has relatively tall and tapered holes compared with CNT emitters, protecting the CNT emitters from the anode field perfectly.In this paper, a new AM cathode is proposed to further improve the intra-pixel uniformity of FED. The developed color AM-CNT FED with TMG was successfully operated with a good uniformity. Figure 1 shows the new AM cathode structure with cascadeconnected a-Si TFTs and CNT emitters. The address TFT, addressing the display signals, and the driver TFT, driving the CNT emitters directly, are series-connected. The address TFT has the normal gate structure meanwhile the driver one has the offset gate with an offset length (L off ) to endure a high voltage needed for field emission through the TMG. The TMG with tapered gate holes not only induces field emissions but also shields the CNT emitters from the anode voltage perfectly, enabling us to apply a very high anode voltage of about 10 KV in high-voltage FED technology. New AM Cathode DesignThe equivalent sub-pixel circuit of the proposed AM cathode is shown in Fig. 2. A single address TFT and multiple driver TFTs have been incorporated in a sub-pixel in which each driver TFT had its own CNT emitters and controlled the CNT emitters separately. AM-CNT FED Fabrication and PerformancesConventional inverted-staggered process was applied to the fabrication of a-Si TFTs for our AM cathode along with 4-mask lithography, which is at least 1 less mask than the TFT-LCD process. The deposition conditions for the active and dielectric layers were adjusted to endure the high-temperature vacuum sealing process. An as-prepared multi-wall CNT powder was mixed with some organic binder, photo-resist, and conducting particles. The mixed CNT paste was formed onto the drain of driver TFTs using screen printing and...

New-Type Planar Field Emission Display with Superaligned Carbon Nanotube Yarn Emitter

“…Superaligned carbon nanotube (CNT) yarn and film have supplied the possibility for the fabrication of CNT devices at large area scale with high uniformity. − For the advantages such as fast response, monochromatic, high brightness, and low power consumption, − field emission is a very hot topic for the application of nanomaterials, especially for one-dimensional materials − due to their high aspect ratio. Field emission of CNT has been widely studied for their exceptional field emission properties, ,,− and it has been reported that superaligned CNT yarn has shown excellent field emission properties. − The application of superaligned CNT yarn in field emission is possible to facilitate the fabrication of large area field emission display (FED) with improved performance, which requires a low cost fabrication process for mass production. The CNT yarn is difficult to integrated into the conventional vertical FED structures, which is adopted by the CNT paste − and Spindt tip. ,, Itoh and et al have fabricated a planar type field emission structure in ref .…”

“…Field emission of CNT has been widely studied for their exceptional field emission properties, ,,− and it has been reported that superaligned CNT yarn has shown excellent field emission properties. − The application of superaligned CNT yarn in field emission is possible to facilitate the fabrication of large area field emission display (FED) with improved performance, which requires a low cost fabrication process for mass production. The CNT yarn is difficult to integrated into the conventional vertical FED structures, which is adopted by the CNT paste − and Spindt tip. ,, Itoh and et al have fabricated a planar type field emission structure in ref . Canon and Toshiba have fabricated surface-conduction electron-emission display (SED), , which is also a planar type structure.…”

“…Figure a shows the traditional vertical triode FED structure that the Spindt type emitter adopted. Several CNT FEDs have also adopted this type of structure. − However, the fabrication process is complex and the post-treatment of the CNT emitters under the gate electrode is difficult. − As has been shown, superaligned CNT yarn shows excellent field emission ability. − However, it is difficult to integrate the CNT yarn emitter into the conventional vertical field emission structure. We have designed a planar FED structure.…”

Field emission behavior study of multiwalled carbon nanotube yarn under the influence of adsorbents

“…[9][10][11] The intrinsic FE of singlewalled CNTs was found to follow the Fowler-Nordheim ͑FN͒ theory, although adsorption effects induced nonlinearity in the FN ͑ln I / V 2 -1 / V͒ curves and produced current saturation phenomena. 9,12 Although the FE of multiwalled CNTs ͑MWCNTs͒ has been studied thoroughly, [5][6][7][8][13][14][15][16] the explanation of the deviation of their FE from FN theory is still controversial. [17][18][19] The details of the deviation of real FN curves from FN theory need to be properly explained for both practical and theoretical reasons.…”