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 sp3rsp2 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=10y5 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 10y6 mbar with 45 mm spacer separating cathode and anode and the sp3rsp2 bond ratio of ta-C films were examined by G-band shift in Raman spectrum. The turn-on electric field was 5.8 Vrmm and emission current density at certain electric field varies with sp3rsp2 bond ratio. It shows at sp3-rich ta-C film, sp2 bonds play an important role supporting emission current while sp3 bonds exhibit a low work function surface. q1999 Published by Elsevier Science B.V. All rights reserved