Field emission from undoped and nitrogen-doped tetrahedral amorphous carbon film prepared by filtered cathodic vacuum arc technique

• Published in: Diamond and related materials Vol. 7; no. 2; pp. 640 - 644
• Main Authors: Cheah, L.K., Shi, X., Tay, B.K., Silva, S.R.P., Sun, Z.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.1998
• Subjects: Doping; Field emission; ta-C; ta-C:N; ta-C:N; Field emission; ta-C; Doping
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(97)00291-4

The field emission results from undoped and nitrogen doped tetrahedral amorphous carbon (ta-C and ta-C:N) prepared by the filtered cathodic vacuum arc (FCVA) technique, deposited on both n + and p +-type Si are reported. The effect of different types of Si substrate and the film thickness on the onset electric field has been investigated. Three sets of ta-C samples with differing doping concentrations were used in the study: undoped p-type ta-C (p-ta-C), nitrogen weakly doped intrinsic 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 explanation for the behavior of the onset electric field measured. The heavily doped hetero-junction, n +-ta-C/p +-Si, demonstrated the lowest onset field of 10 V μ −1 with current densities of 0.1 mA mm −2 at 50 V μm −1 due to the Zener tunneling arising from the severe band bending. A film thickness of 30–40 nm is more favorable for field emission due to the ease with which the film can be fully depleted. At some locations of i-ta-C films, various types of craters were formed after an electrical discharge at a high field (∼58 V μm −1) followed by a subsequent reduction in the onset field to about 15 V μm −1.