Use of low-energy ion assistance for the modification of diamond-like carbon films conductivity

Abstract

Results for DLC films produced by vacuum condensation of carbon plasma created by a pulsed-arc accelerator are presented. Coatings were irradiated by argon ion beams with an energy of 40–90 eV and an ion current density of 50–200 μA/cm 2. Electron-diffraction results show, that the coatings deposited both with and without ion assistance are amorphous. In comparison with films obtained without ion assistance, the surface resistance of the irradiated films decreased from 10 10–10 11 to 10 5–10 8 Ω/square. It has been found that the film conductivity was thermally activated. The value of the activation energy for non-irradiated and irradiated films was determined to be 0.94 and 0.49 eV, respectively. These films have a negative temperature coefficient of resistance, it is 4–5 less for the irradiated films. X-ray photoelectron spectroscopy has been used to determine the elemental composition and chemical compounds of the irradiated films. A method of manufacturing high resistance low noise miniature resistors is proposed in which a thin modified layer (skin-layer) having a small temperature coefficient of resistance and simultaneously a high surface resistance is formed on the DLC-film surface.