Effects of composition on field emission character of tetrahedral amorphous carbon

The character of low work function and chemical inner of tetrahedral amorphous carbon (ta-C) show great potential application on Vacuum Microelectronic Devices for cathode coating, such as field emission display (FED). The field emission character of ta-C film owes to sp(3)/sp(2) bonds ratio, depending on deposition process. In this work, ta-C films were deposited by pulsed laser deposition (PLD) using excimer laser (193 or 248 nm) in an atmosphere of 2 x 10(-5) mbar. By ablation of graphite target on focus of laser beam, ta-C were deposited on Si substrate in a distance of 8 cm to target. Field emission of ta-C film were carried out in an atmosphere of 10(-6) mbar with 45 mu m spacer separating cathode and anode and the sp(3)/sp(2) bond ratio of ta-C films were examined by G-band shift in Raman spectrum. The turn-on electric field was 5.8 V/mu m and emission current density at certain electric field varies with sp(3)/sp(2) bond ratio. It shows at sp(3)-rich ta-C film, sp(2) bonds play an important role supporting emission current while sp(3) bonds exhibit a low work function surface. (C) 1999 Published by Elsevier Science B.V. All rights reserved.