Lk. Cheah et al., FIELD-EMISSION FROM UNDOPED AND NITROGEN-DOPED TETRAHEDRAL AMORPHOUS-CARBON FILM PREPARED BY FILTERED CATHODIC VACUUM-ARC TECHNIQUE, DIAMOND AND RELATED MATERIALS, 7(2-5), 1998, pp. 640-644
The field emission results from undoped and nitrogen doped tetrahedral
amorphous carbon (ta-C and ta-C:N) prepared by the filtered cathodic
vacuum are (FCVA) technique, deposited on both n(+) and p(+)-type Si a
re reported. The effect of different types of Si substrate and the fil
m thickness on the onset electric field has been investigated. Three s
ets of ta-C samples with differing doping concentrations were used in
the study: undoped p-type ta-C (p-ta-C), nitrogen weakly doped intrins
ic ta-C (i-ta-C) and nitrogen heavily doped n(+)-type ta-C (n(+)-ta-C)
. The heterojunction-based field emission model gives a reasonable exp
lanation for the behavior of the onset electric field measured. The he
avily doped hetero-junction, n(+)-ta-C/p(+)-Si, demonstrated the lowes
t onset field of 10 V Irm-l with current densities of 0.1 mA mm(-2) at
50 V mu m(-1) due to the Zener tunneling arising from the severe band
bending. A film thickness of 30-40 nm is more favorable for field emi
ssion due to the ease with which the film can be fully depleted. At so
me locations of i-ta-C films, various types of craters were formed aft
er an electrical discharge at a high field (similar to 58 V mu m(-1))
followed by a subsequent reduction in the onset field to about 15 V mu
m(-1). (C) 1998 Elsevier Science S.A.