AVS 50th International Symposium
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuM

Paper SE-TuM8
The Effect of Surface Finish on Field Emission in Nitrogen-implanted, Silicon Dioxide-Coated Stainless Steel

Tuesday, November 4, 2003, 10:40 am, Room 323

Session: Nanostructured, Nanocomposite, and Functionally Gradient Coatings
Presenter: N.D. Theodore, College of William and Mary
Authors: N.D. Theodore, College of William and Mary
D. Manos, College of William and Mary
C. Hernandez, Jefferson Lab
T. Wang, Jefferson Lab
H.F. Dylla, Jefferson Lab
R. Moore, University at Albany Institute for Materials
Correspondent: Click to Email
The purpose of this study was to assess the changes in tunneling parameters associated with field emission from processed stainless steel surfaces, as a function of their prior surface finish. According to Fowler-Nordheim theory (FNT), field emission from a material is governed by two parameters, alpha and beta, which relate to the work function of the material and to its surface morphology. Thus surface roughening may lead to large changes in field emission due to geometrical enhancements associated with sharp features. In this paper, six 304 stainless steel disks were hand-polished to different finishes, ranging from 1 micron to 30 microns rms roughness. These disks were then coated with a nitrogen-implanted silicon dioxide layer. @footnote1@ Depth Auger electron spectroscopy revealed that the thickness of the coating is approximately 240 nm. Field emission spectroscopy maps, STM maps, and AFM and DekTek scans were also taken of each sample. Data from these scans as well as the compositional character of the coating will be presented. Results show that despite surface morphology, each sample possessed 1-3 emission sites, producing current of 2nA at each emitter at threshold electric fields above 85 MV/m. The coated samples have comparable field emission I-V curves. An interpretation of these data in terms of a total electron energy FNT model will be discussed.@footnote 1@C. Sinclair, et al. Proccedings of the 2001 Particle Accelerator Conference. Chicago, IL, 2001.