Field emission from modified nanocomposite carbon films prepared by filtered cathodic vacuum arc at high negative pulsed bias

Cobalt-containing amorphous carbon (a-C:Co) composite films have been prepared by filtered cathodic vacuum arc at high negative pulsed bias voltage. After heat treatment at 580 °C in a mixture of acetylene and hydrogen gases, field emission properties of the a-C:Co films were significantly improved and the films deposited at higher negative bias voltage possessed better field emission properties. A relatively low threshold field of 2.1 V/μm (for emission current 1 μA/cm ² ) and a high emission current density of 2 mA/cm ² at the electric field of 6 V/μm has been achieved for the films deposited at the negative bias voltage of 7 kV. The morphologies and structures of the a-C:Co films were also studied in detail. It is suggested that the employed negative bias voltage increases the grain size and the sp ² content in the films, and further improves the field emission properties.