Papers

ICMCTF1999 Session D3/G8: Electronic and Optical Applications of Diamond and Related Materials

Thursday, April 15, 1999 1:30 PM in Room Forum/Senate/Committee

Thursday Afternoon

Start	Invited?	Item
1:30 PM		D3/G8-1 Electrical and Optical Properties of Diamond-like Carbon A. Grill (IBM Research Division) Diamond-like carbon (DLC) films, amorphous hydrogenated or non-hydrogenated forms of carbon, are metastable amorphous materials characterized by a range of attractive mechanical, chemical, tribological, as well as optical and electrical properties. The films can be prepared at low temperatures, from a large variety of precursors, by a diversity of techniques, and their characteristics can be modified by incorporation of different elements such as N, F, Si, or metals. The diversity of methods used for the deposition of DLC films provides the flexibility to tailor their properties according to specific needs and potential applications. The optical gap of these materials is in the range of 1-4 eV and the electrical resistivity spans 14 orders of magnitude. The dielectric constant of DLC films covers the range of 2.5-6. The talk will review the optical and electrical characteristics of DLC and discuss the actual and potential applications based on these properties.
2:10 PM		D3/G8-3 Large Area Deposition of Field Emission Cathodes for Flat Panel Displays A.F. Jankowski, J.P. Hayes, J.D. Morse (University of California - LLNL) Field emission cathodes (FECs) with characteristics of cold emission, low voltage operation, high current density and microscopic size meet the requirements of an electron source for use in vacuum microelectronics. Prior efforts focused on deposition techniques, as electron beam evaporation, to produce the size and shape of cathode required for efficient operation. After two decades of development, the convention for FEC synthesis involves coating with a very-high tolerance in thickness uniformity using a planetary substrate fixture and a large source-to-substrate seperation. New criteria for a deposition process must facilitate a reduction in the operating voltage by increasing the density of emitters through a reduction of cathode size and spacing. In addition, the objective of scaling the substrate size from small (less than 30 sq cm) to large (greater than 500 sq cm) areas has compounded the manufacturing requirements to a point beyond that obtainable through modifications to the convention for FEC deposition. A new patented approach to design, assemble, and operate a coating system enables FEC deposition over large areas through the control of source divergence coupled to incremental substrate positioning. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.
2:30 PM		D3/G8-4 Improvement of the Wear and the Corrosion Resistance of C/Al-Composites by Diamond-like Carbon Coatings A. Dorner, B. Wielage (TU Chemnitz, Germany) Because of the extreme sensitivity of carbon fiber reinforced aluminum (C/Al-Compound) to electrochemical corrosion suitable protection methods are necessary. Corrosion control can be achieved by applying appropriate coatings. Diamond-like carbon (DLC) coatings provide properties, which make them interesting materials for external corrosion protection of MMCs (Metal Matrix Composites). Not only the hydrogenerated, amorphous carbon coating reveals outstanding wear resistance and good adherence to the heterogeneous MMC-substrate, but effects a considerable improvement of corrosion resistance. The lightweight and dense DLC-coating covers up the underlying substrate and separate the MMC from the attacking electrolyte (Fig. 1). Fig.1: Carbon fiber reinforced aluminum with diamond-like carbon coating, SEM The electrochemical corrosion behavior of uncoated and DLC-coated C/Al-Compounds is tested in 3,5 wt% NaCl solution by using potentiodynamic polarization and simple immersion tests. It has been found that the pitting potential is shifted significantly in the anodic direction and the corrosion current density is much lower due to the presence of the sealing DLC-coating. Additionally, TEM and SEM studies were performed in order to characterize the fiber-matrix interface and the corrosion mechanisms of uncoated and DLC-coated MMCs.
2:50 PM		D3/G8-5 Electron Field Emission from Amorphous Carbon Nitride by ECR-CVD Synthesis H.C. Shih, S.H. Tsai, X.W. Liu (National Tsing Hua University, R.O.C.); J.W. Chao (Naitonal Chung Hsing University, R.O.C.) Experiments have been designed for the systhesis of amorphous carbon nitride film on silicon wafer by ECR-CVD equipped with a dc bias voltage in a gas mixture of C₂H_{2, N}sub 2, and Ar and followed by surface sputtering in a pure Ar plasma in the presentce of an applied dc bias. Such non-lithographic flat panel of CN film exhibits an onset of electron field emission as low as 6 V/µm. The structural and compositional modification by Ar plasma treatment are distinct and therefore characterize by the following techniques: FTIR, XPS, Raman spectroscopy, AFM and OES. The outcome of the result is mainly because of the surface roughness that is adequate to the electron field emission for synthesis of amorphous carbon nitride films by ECR-CVD.
3:30 PM		D3/G8-7 Field Emission Display Development at Motorola A.A. Talin (Motorola) Over 12 years have passed since the first field emission display (FED) prototype, a 5" diagonal, ¼ VGA monochrome screen, was built by LETI, France. Now, commercially available screens of similar design are finally beginning to emerge. These displays, manufactured by PixTech Inc., are based on a low-anode-voltage (<1kV) concept, and are geared primarily for instrumentation applications. However, in order to challenge AMLCDs and ultimately the CRT beyond niche applications, FED screens of superior image quality, including brightness and color purity, must be produced. To this end, Motorola adopted a high-anode-voltage approach to FED design, producing full-color, sun light readable FED prototypes. In my presentation, I will address some of the challenges faced in producing a high-anode-voltage FED. In addition, I will describe some of the ongoing efforts at Motorola to produce still cheaper and more reliable displays, such as those based on carbon cathodes as opposed to molybdenum microtips.
4:10 PM		D3/G8-9 Electron Field Emission and Secondary Electron Emission Characteristics From Cesiated Amorphous Carbon Films D.W. Han (Yonsei University, KOREA); Y.H. Kim, D.J. Choi, H.K. Baik (University, KOREA) We have deposited neutral Cs and C^-ion beams on silicon substrates with various carbon ion energy( 20eV - 200eV) to synthesize cesiated amorphous carbon films for investigation of field emission and secondary electron emission characteristic. The properties of cesiated amorphous carbon films were investigated using x-ray photoelectron spectroscopy, Raman spectroscopy, and atomic force microscopy. As the carbon ion energy increased, relative sp³ratio increased, and surface roughness decreased. The field emission characteristic of the amorphous carbon films as a function of carbon ion energy was examined by diode type I-V measurement at ultra high vacuum system. From I-V measurement, the turn-on field with range from 10V/µm to 20V/µm is obtained. Electron beam of 3keV is used for the evaluation of secondary electron emission ratio, which is varied from 0.46 to 0.74. In this study, we investigated that the relation among carbon ion energy and field emission and secondary electron emission. And the effect of Cs in the films was examined as well.
4:30 PM		D3/G8-10 Field Emission Properties of Nanostrucured Carbon Films C.F. Meyer, H.-J. Scheibe, P. Siemroth (Fraunhofer - Institut f. Werkstoff und Strahltechnik, Germany); G. Mueller, K. Theinissen (Bergische Universitdt Wuppertal, Germany); B. Schultrich (Fraunhofer Institut f. Werkstoff und Strahltechnik, Germany); H. Banzhof (Technische Universitdt Dresden, Germany) Field emitting cathodes are the basic element for FED. Carbon represents a very promising candidate. Apart from a high electron emissivity a high geometrical field enhancement is indispensable. Instead of an artificial structurization of sharp cones (spindth cathodes) this may be achieved by smooth films with an internal naturally grown nanostructure. By a modified Laser-Arc technique dense carbon films have been prepared with a nanostructure of graphitic and diamond-like regions. TEM investigations revealed the onion-like structure of concentric graphitic shells embedded in an isolating diamond-like matrix. Investigation of the field emission shows low threshold values and the high stability and reproducibility of the emission characteristics of these films. By using a special field emission scanning probe the distribution of the emitting spots has been explored.