Developments in Ceramic Materials Research

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242 Development of Display Technology Li Chen INTRODUCTION The display is such a critical human interface of electronic entertainment system that experts from academia as well as industry have been working for decades to create them larger, lighter, brighter, and thinner - particularly for television receivers and computer monitors. There have been different technologies such as Cathode Ray Tube (CRT), Thin Film Transistor Liquid Crystal Display (TFT-LCD), Plasma Display Panel (PDP), Organic Light Emitting Diode (OLED) display emerged since the last century, and promised to take the display industry where it has never gone before. They all were expected to gain wide acceptance for use as television receivers. Today’s display market offers an abundance of choices of these technologies, each with their own advantages and disadvantages. CRT displays are heavy, bulky, and limited in size for direct view applications. PDPs are very electrical power hungry, suffer from lower brightness, and have the potential for screen burnin. TFT-LCDs are limited in size due to manufacturing constraints, are costly, and suffer from narrow viewing angle and slow refresh rates. OLEDs suffer from stability and lifecycle issues. The introduction of High Definition Television (HDTV) spurs display industry even further. HDTV provides means for transforming entertainment experiences by delivering crystal clear video in high resolution, high-fidelity surround sound, and the ability to drive interactive applications. Take-up of high definition services is accelerating in the USA and in other countries. With Sky's announcement that it has been examining the technical details for a launch of high definition services, and BBC increasing its amount of ongoing and archive programming broadcast as part of its HDTV trial, it now appears that HDTV will become a reality in the UK over the next few years. Because of the inherent flaws in current display technology for HDTV, researchers have turned to micro tip based Field Emission Display (FED) and carbon nanotubes based FED to create a new class of large area, high resolution and low cost flat panel displays. Researchers believe that FED is the technology of choice for ultra high definition, wide screen televisions. It is this technology that will be able to support the HDTV revolution at adequate cost. The FED technology shares many similarities with traditional CRT technology. As for FED and CRT, electrons are extracted out of electron gun(s), and are accelerated in vacuum towards phosphor coated faceplate anode, collide with phosphor to create illumination through conventional process of electroluminescence [1]. The main difference is that, for FEDs, electrons are generated from cold micro field emitters rather than thermal emitters. Therefore the device consumes much less electrical power, and displays can be turned on instantly. Instead of one single point electron gun in a monochrome CRT or three point electron guns in a colour CRT, in a FED, each pixel comprises arrays of micro field emitters from which electrons are emitted [2]. In a CRT, electrons emitted from its electron source are deflected and scanned across the phosphor screen under the action of electromagnetic deflection coils to produce an image, while in a FED, hundreds if not thousands electron micro cathodes in high density are used for lighting each pixel. Thus there is no need of the bulky electromagnetic deflection coils for scanning the electron beam, and no need for refocusing individual electron beam [3]. Electrons emitted from the micro cathodes site directly below
Field Emission Display on Ceramic 243 the phosphors of a pixel to create an image, as a result the panel thickness can be reduced down to several millimetres [4]. Another advantage of a FED structure over a CRT is the reduction in the number of drivers by a factor of three (one single emitter sends electrons towards a sub-pixel which is successively red, green and blue). Field Emission Display Technology and Advanced Ceramics Technology For an electron to leave a material, the electron must gain energy to exceed the work function, which is a potential barrier at the surface of a metallic conductor that binds electrons to the material. This can be accomplished in a variety of ways, including thermal excitation in the case of thermionic emission, electron and ionic bombardment in the case of secondary electron emission, and the absorption of photons in the case of photoelectric emission. Field emission differs from all these forms of electron emission in that the emitted electrons do not gain an energy which exceeds the material’s work function. Field emission phenomenon results from the tunnelling of electrons from a metal or a semiconductor into the vacuum under an application of a strong electric field. The high electric field applied to the vicinity of the surface of a substance to low and thin the potential barrier on the surface, so that free electrons with high potential energy inside the substance can have possibility to tunnel through the thinned potential barrier and leave the surface. Since there is no heat transfer involved in the electron emission, field emitters are called cold cathode electron source [5]. To achieve a low operating voltage of a cold field emitter, in the case of a micro tips based FED, the tips are manufactured into very sharp form so that the local electric field strengths become high enough for even a moderately low voltage applied to the adjacent gate electrode [6]. Using a low work function material could also significantly reduce the turn on gate voltage for a field emitter. The most popular low work function material for forming a micro tip is molybdenum [7]. The micro tip field emitter fabrication technique was initially invented by Dr. Charles A. “Capp” Spindt at the Stanford Research Institute (now called SRI International) in 1968 [8]. The principal component of a Spindt cathode comprise a basic triode structure: a bottom cathode conducting layer, on which molybdenum micro tips in conical shape reside; a top gate conducting electrode layer, and an insulating oxide layer in between [9]. In the fabrication process, molybdenum cones with tip radii less than 30 nm are deposited by electron beam evaporation into the emitter wells. The cone forming process is self aligned. The advantages of such a structure include the high electron drawing efficiency since the electron emission portion is arranged in the vicinity of the centre of gate electrode where the electric field is most concentrated, the in-plane uniformity of drawn current is high, and the directivity of electron emission is regular, compared to the other field emission device. Spindt’s development stimulated the technology further into a concept to use field emitter arrays in a matrix addressed display (FED) conceived by the SRI team of which Spindt was a member, and patented by M. E. Crost, K. R. Shoulders and M. H. Zinn in 1970 [10]. By 1972, the SRI group had overcome more engineering problems to demonstrate to their satisfaction that it was feasible to manufacture FEDs [11]. Their new fabrication methods were patented by C. A. Spindt, K. R. Shoulders, and L. N. Heynick in 1973 and 1974 [12, 13, 14]. However SRI was unable to obtain funding to develop the FED concept in the decades of the seventies and early eighties. The idea was picked up and the initiative to develop the
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DEVELOPMENTS IN CERAMIC MATERIALS R
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Copyright © 2007 by Nova Science P
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PREFACE Ceramics are refractory, in
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Preface ix crystals is discussed. A
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Preface xi spectra and the directio
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2 Leslie G. Cecil comprehensive dat
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4 Leslie G. Cecil Ringle et al. (19
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6 Leslie G. Cecil The main architec
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8 Leslie G. Cecil can study “the
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10 Leslie G. Cecil Middleton et al.
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12 Leslie G. Cecil The laser ablate
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14 Leslie G. Cecil There are two ge
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16 Leslie G. Cecil distinct recipes
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18 Leslie G. Cecil second group (Fi
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20 Leslie G. Cecil The Vitzil-Orang
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22 Leslie G. Cecil Table 3. Mahalan
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24 Leslie G. Cecil Ixlú and Ch’i
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26 Leslie G. Cecil structures (D. R
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28 Leslie G. Cecil paste and Macanc
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30 Leslie G. Cecil Bieber, A. M. Jr
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32 Leslie G. Cecil Kepecs, S. M., a
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34 Leslie G. Cecil Schele, L., Grub
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36 Z. C. Li, Z. J. Pei and C. Tread
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54 T. T. Basiev, V. A. Demidenko, K
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62 I, % 100 80 60 40 20 0 T. T. Bas
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68 Fluorescence, a.u. 1 T. T. Basie
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70 Fluorescence, a.u. 1 0.1 0.01 0.
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78 k, cm -1 20 18 16 14 12 10 8 6 4
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82 Photon counts 300 250 200 150 10
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84 Fluorescence, a.u. I transfer ,
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86 ln(I transfer (t)) -4.2 -4.4 -4.
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88 Fluorescence, a.u. I transfer ,
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In: Developments in Ceramic Materia
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Synthesis, Spectroscopic and Magnet
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a c Synthesis, Spectroscopic and Ma
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Transmission Transmission Transmiss
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Sm (J/Kmol) Sm (J/Kmol) 15 10 5 Syn
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Intensity (a.u.) Intensity (a.u.) 8
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The Use of Ceramic Pots in Old Wors
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3.2. Wall-in Positions The Use of C
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IACC ( τ ) = t2 ∫ The Use of Cer
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where σ res is the scattering cros
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D50 0.8 0.7 0.6 0.5 0.4 0.3 The Use
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Definition (D50) 1 0.95 0.9 0.85 0.
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Modeling of Thermal Transport in Ce
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Page 258 and 259: 244 Li Chen technology moved to the
Page 260 and 261: 246 Li Chen The continuing evolutio
Page 262 and 263: 248 Li Chen the back contact cathod
Page 264 and 265: 250 Li Chen Figure 3. Vertical side
Page 266 and 267: 252 Li Chen Figure 6. Molybdenum mi
Page 268 and 269: 254 Li Chen Figure 8(a). I-V curve
Page 270 and 271: 256 Li Chen Figure 9. Life time tes
Page 272 and 273: 258 Figure 11(a). Plasma generated
Page 274 and 275: 260 Li Chen [13] C.A. Spindt, K.R.
Page 276 and 277: 262 S. Ardizzone, C. L. Bianchi, G.
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Developments in Ceramic Materials Research

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