AVS 50th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS-TuP

Paper NS-TuP4
The Effects of Molybdenum-Oxide and Diamond on Field Emission

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: T. Tyler, North Carolina State University
Authors: T. Tyler, North Carolina State University
D. Jaeger, North Carolina State University
A. Kvit, North Carolina State University
V. Zhirnov, Semiconductor Research Corporation
J. Hren, North Carolina State University
Correspondent: Click to Email
Refractory metals such as molybdenum and tungsten are frequently used in field emission applications, most often in the form of single tips or arrays of tips. Such field emitters have been studied in great detail over the past thirty years. The addition of an 'intentional' coating material (e.g. dielectric deposits such as aluminum-oxide or diamond) to improve emitter performance has been widely studied as well. However, there has been a lack of control of substrate effects (e.g. the presence and nature of oxides) in combination with coating effects. Carefully controlled morphological and compositional information is now required for a more complete analysis. We report here on combined studies of field emission, with high-resolution transmission electron microscopy (HRTEM), with computer simulations of local electric fields. Current versus voltage data is obtained during field emission, while HRTEM is used to determine morphology and composition (using electron energy loss spectroscopy). Computer simulations of electrostatic effects, employing finite element methods, are then conducted using the morphologic and compositional information of the composite emitter structure, obtained from HRTEM. The magnitude and distribution of the surface potential barrier and the local field strength at the apex of the field emitter can thus be determined. The results also can provide information on the materials' electronic properties, such as the dielectric constant, trap density, and carrier velocity. The non-destructive nature of these experiments makes comparison studies possible; e.g. molybdenum needles, both oxidized and non-oxidized, are compared with needles coated with layers of nano-diamond.