No abstract

Diamond has existed in the natural state for thousands of years. It was mainly used as a jewel for its optical brilliance and for its hardness. In the 1950s methods were developed to fabricate synthetic diamonds commercially. This greatly increased diamond's industrial use, mostly for grinding and lapping applications. Diamond is a crystalline form of carbon, a group-IV element in the periodic table. Silicon and germanium are also Group-IV elements and also have the same crystalline lattice structure as diamond. Hence there has been theoretical interest in diamond's electronic properties since the beginning of the semiconductor age. However the cost and poor crystalline quality of both natural and synthetic diamond have precluded any real industrial interest in diamond as an electronic material. Methods of low-temperature and low-pressure diamond-film deposition, developed initially by the Russians in the 1950s and 1960s (and thence by the Japanese, and eventually by others) has made it possible to use this exotic material as an electronic substrate.Diamond, in single-crystalline, polycrystalline, and diamondlike carbon (DLC) forms, is a material with many unusual properties. It is the hardest naturally occurring material, the most thermally conductive, and the most transparent. It also has the slickness of Teflon. In regard to many physical properties, it is at the extreme end of the scale. One of the more unusual and important properties that it possesses is its presentation of a rather small barrier to the emission of electrons into a vacuum.

We have developed field-emission-display technology driven by chemical-vapordeposition-grown carbon-nanotube emitters incorporated in a simple, low-cost device structure. Here, we report on frit-sealed test displays with a brightness of 3000 cd/m 2 at 3 kV and a lifetime of 9000 hours with only 45% degradation. We also demonstrate the scalability of the technology with a uniform high-brightness 6-in. QVGA that displays video images with a switching voltage of 40 V. FIGURE 1 -Cross section of the cathode structure.FIGURE 2 -SEM view of part of a cathode which shows pads covered with CNTs in between the gates.

Field emission displays, due to their low driver electronics cost, are a competitive technology for large area flat screen displays. They are particularly well-suited for HDTV resolution displays which incorporate an enormous number of driver outputs. Here we demonstrate the suitability of nanotube-based field emission technology to obtain a high performance full-color display with 726 µm pixels, the proper size for a 42" 1280x720 HDTV resolution display. We report results of brightness, beam divergence, and uniformity measurements, and we show RGB color video images.

The fabrication of an efficient cold cathode emitter from carbon is based on a combination of material properties, which must be carefully tailored during deposition. We present the electron emission characteristics of several carbon films deposited by cathodic arc evaporation, and their correlation with the chemical composition, microtexture and microstructure of the films. The emission threshold field voltage, emission site density, uniformity and stability of both tetrahedral amorphous carbon, nitrogen doped carbon and nanoclustered carbon films will be reviewed. We will also address issues related to the deposition method, such as substrate temperature, defect density and scalability, in connection with requirements for the fabrication of field emission displays.