Nitrogen containing hydrogenated amorphous carbon prepared by integrated distributed electron cyclotron resonance for la
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Nitrogen containing hydrogenated amorphous carbon prepared by integrated distributed electron cyclotron resonance for large area field emission displays N. M. J. Conway, C. Godet, B. Equer Laboratoire de Physique des Interfaces et Couches Minces, Ecole Polytechnique, 91128 Palaiseau-Cedex, FRANCE ABSTRACT The field emission properties of hydrogenated amorphous carbon containing up to 29at% nitrogen (a-C:N:H), grown in an integrated distributed electron cyclotron resonance (IDECR) reactor were studied using a sphere-plane geometry. All films were smooth in character and required a high field (20-70V/µm) activation process before emission, which created micronsized craters in the emission region. Further analysis suggested that the emission originates from activation-created geometrically enhanced areas around the crater region. Upon low-level nitrogen incorporation (N/N+C≤0.2), the field required for activation decreased from 54V/µm to a minimum value of 20V/µm. The turn-on field required for 1µA of current also decreased, reaching a minimum of 11.3V/µm. The decrease in activation and turn-on field was related to the increase in conductivity observed with increasing nitrogen content. At higher nitrogen concentrations, the increase in activation energy and turn on field for emission may be due to changes in overall material structure, as indicated by the decreasing optical gap INTRODUCTION The field emission properties of carbon-based materials have attracted a great deal of attention with regards to their potential use as cold cathodes in field emission displays (FEDs) due to their ability to emit electrons from nominally flat, or intrinsically geometrically enhanced films at low electric fields. [1-5] It was initially thought that the good emission properties of diamond and diamond-like carbon could be related to the low, or even negative, electron affinity of the material. However, similar emission characteristics can be obtained from graphite-based, and hence high work function, nanotubes and nanoclusters [4,5]. Furthermore, it has been shown that electrons are actually emitted from the grain boundaries in diamond rather than the grains themselves[6] with a work function similar to that of graphite[7]. It is clear therefore that the emission mechanism is still not fully understood [8]. For carbon-based field emission displays to be feasible from an industrial perspective, it should be possible to grow them over large areas, at high deposition rates and at low temperatures (so that low cost substrates can be used). The majority of current deposition methods do not meet these criteria, often requiring high deposition temperatures or using ion beam or magnetic confinement techniques not easily scaleable to large areas. In contrast, the integrated distributed electron cyclotron resonance (IDECR) reactor used in this study satisfies all these criteria; its high density plasma produces a high deposition rate and the deposition area can be easily scaled up due to its unique design, as will be discussed in the experimental
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