Field emission properties of nitrogen-doped diamond-like carbon films deposited by direct metal ion beam deposition
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Field emission properties of nitrogen-doped diamond-like carbon films deposited by direct metal ion beam deposition Kie Moon Song1, Namwoong Paik2, Steven Kim2, Daeil Kim2, Seongjin Kim2, Ju Youn Kim3, and Hyeongtag Jeon3 1 Department of Applied Physics, Konkuk University, Chungju 380-701, Korea 2 SKION Corporation, 50 Harrison St., Hoboken, NJ 07030 3 Division of Materials Science and Eng., Hanyang University, Seoul 133-791, Korea ABSTRACT Nitrogen-doped diamond-like carbon (DLC) films were deposited on a silicon substrate by direct metal ion beam deposition (DMIBD). Partial pressures of nitrogen gas were changed to get different compositions of nitrogen in the DLC films. The composition and surface morphology of the films were examined using X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). Effect of nitrogen doping on field emission property was studied. The field emission data indicated that the nitrogen doping lowered the turn-on field and increase the current density. It was believed that doping of nitrogen into the DLC film plays an important role in enhancement of the field emission. This enhancement of field emission could be explained by the improvement of electron transport through nitrogen-dope DLC layer.
INTRODUCTION Conventional cold cathodes usually have been fabricated as arrays of gated microtips of sharp tips, in order to produce a large geometrical enhancement factor for the local electric field, as well as high emission site density. An alternative approach that would completely eliminate the complicated and expensive fabrication of large, high-density arrays of field emission tips is to use a thin-film cathode material that has either a very low electron affinity or intrinsic nanostructure to provide a sufficiently high geometrical enhancement factor. Now many researchers are considering DLC films as one of electron-emitting cathode materials for cold field emission displays [1] due to their unique properties such as low or negative electron affinity (NEA), low work function, high thermal conductivity, and outstanding chemical inertness [2]. Moreover DLC films can easily be deposited over large areas, on many kinds of substrates, even at room temperature. Recently, there have been several attempts to improve the properties of DLC films by the addition of elements, such as silicon, nitrogen, fluorine, and various metals [3-5]. Nitrogen incorporation in DLC films has been shown to reduce optical band gap and to increase the conducting part of the film by the decrease of the sp3 bond fraction. This conducting part plays an important role as a electron path and also contributes to the field enhancement [6]. In this paper, we have reported some physical and field emission properties of nitrogendoped DLC films prepared by direct metal ion beam deposition (DMIBD). P8.25.1
EXPERIMENTAL SETUP DLC films deposited using a direct metal ion beam deposition method. To reduce the work function of the sputtering target, Cs vapor was introduced into the chamber by extracting the Cs clu
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