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

摘要

The field emission results from undoped and nitrogen doped tetrahedral amorphous carbon (ta-C andta-C:N) prepared by the filtered cathodic vacuum arc (FCVA) technique, deposited on both n{sup}+and p{sup}+ -type Si are reported. The effect of different types of Si substrate and the film thicknesson the onset electric field has been investigated. Three sets of ta-C samples with differing dopingconcentrations were used in the study: undoped p-type ta-C (p-ta-C), nitrogen weakly doped intrinsicta-C (i-ta-C) and nitrogen heavily doped n{sup}+ -type ta-C (n{sup}+ -ta-C). The heterojunction-based field emission model gives a reasonable explanation for the behavior of the onset electric fieldmeasured. The heavily doped hetero-Junction n{sup}+ -ta-C/p{sup}+ -Si, demonstrated the lowestonset field of 10 V μm{sup}-1 with current densities of 0.1 mA mm{sup}-2 at 50 V μm{sup}- 1due to the Zener tunneling arising from the severe band bending. A film thickness of 30-40 nm is morefavorable for field emission due to the ease with which the film can be fully depleted. At somelocations of i-ta-C films, various types of craters were formed after an electrical discharge at a highfield (～58 V μm{sup}-1) followed by a subsequent reduction in the onset field to about 15 V μm{sup}-1.