Enhanced electron field emission properties of diamond-like carbon films using a titanium intermediate layer

Abstract

Substantially improved uniformity and enhanced electron field emission properties of hydrogen-free diamond-like carbon (DLC) films were obtained using a titanium intermediate layer after the annealing process. Large emission current densities of 2.08 mA cm-2 at 14.3 V µm-1 and 7.20 mA cm-2 at 25.7 V µm-1 were achieved for DLC/Ti/Si film annealed at 430 °C for 0.5 h. Its field emission was much more uniform than that of as-prepared DLC/Ti/Si and DLC/Si films. Secondary ion mass spectroscopy (SIMS) showed that C has been amply diffused into the Ti layer. An x-ray photoelectron spectroscopy (XPS) spectrum of the annealed DLC/Ti/Si film after 10 min of argon ion sputtering showed the formation of TiC at the interface between the DLC and Ti/Si substrate. This interaction and interdiffusion of C and Ti could significantly lower the Schottky barrier height between the DLC and Ti/Si substrate. The result was that electrons induced from the Ti/Si substrate can be easily penetrated into DLC films, which enhances the field emission properties.

Annealing effect on electron field-emission properties of diamond-like nanocomposite films

“…The field-emission measurement has been described in detail elsewhere. 19 The area of all the samples tested is 0.3ϫ0.4 cm 2 . The electric field ͑F͒ is calculated by dividing the anode voltage by the anode-cathode distance, and the emission current density ͑J͒ is obtained assuming that the emission occurred uniformly over the entire surface of the film exposed to the anode.…”

“…11 Excellent electron field-emission characteristics with low turn-on electric field and high current density have been observed from various materials, such as, graphite, 12 carbon nanotubes, 13,14 conductive polymer composites, 15 diamond, [8][9][10][11] and diamond-like carbon ͑DLC͒ films. [16][17][18][19] Among them, diamond and DLC films are viewed as the most promising materials for cold cathode emitters because of their unique advantages, such as low or negative electron affinity, chemical inertness, high mechanical stability, high thermal conductivity, and simplicity of processing ͑low cost͒. DLC is especially interesting as, unlike diamond, it can be deposited on various substrates, such as metal, silicon, plastic, and glass, over large areas with excellent uniformity at room temperature.…”