Electron Emission From Diamond Films

Diamond always has been considered an exciting material. In addition to its other outstanding properties, diamond's capacity for cold electron emission has become a “hot” topic of research in recent years. The electron emission from diamond films is important for both fundamental and applied purposes, which may be expressed by two questions as follows: “Why does diamond emit electrons?” and “How can an efficient cold cathode be made?”The “diamond-emission era” started in 1991. That year three papers were published, reporting unexpectedly high electron emissivity from diamond. The first paper by Djubua and Chubun was very practical, having been written by device engineers. They tried different materials for the fabrication of pointed field emission cathodes and found that emitters made from diamondlike carbon (DLC) demonstrated a lower emission threshold compared to other materials. A second paper by Wang et al. reported a low emission threshold for chemical-vapor-deposition (CVD) diamond films, whereas a third paper by Geis et al. described the fabrication and operation of diamond cold cathodes.Since 1991 hundreds of papers about electron emission from diamond and diamondlike materials have been published. The motivations for this increasing activity are prospective applications in vacuum microelectronics—that is, vacuum emission devices fabricated by modern microelectronic technologies. Experts expect that combining the physical advantages of emission devices and the technological progress in solid-state microelectronics will result in the development of an entirely new generation of high-performance electronic devices—among them, flat-panel displays and miniature microwave tubes.