Doctoral Dissertations

Keywords and Phrases

Diamond Films; Field Emission; Field Emitter Arrays; Flat Panel X-Ray Source; Microfabrication; N-UNCD

Abstract

"As an alternative to conventional X-ray sources, a flat panel transmission X-ray source is being developed. A field emitter array (FEA) prototype to be incorporated as cold cathode in this flat panel X-ray source was fabricated for this work. Using the Particle-in-Cell code OOPIC Pro, an initial FEA was designed through simulations. Based on the simulation results, a FEA prototype was fabricated using conventional microfabrication techniques. Planar nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) films were used as field emitters. This N-UNCD based FEA prototype was composed of 9 pixels distributed in a 3x3 array, with a pixel size of 225x225 µm, and a 500 µm pitch. Each pixel was composed of a N-UNCD-based cathode and a free-standing copper grid used as extraction grid. Field emission from each pixel could be addressed individually. Emission currents per pixel in the order of 0.05 - 3.0 µA were obtained for extraction fields between 4 and 20 V/µm. Delamination issues were found in the microfabrication of the first FEA prototype. Consequently, a second generation N-UNCD based 3x3 FEA was designed and fabricated. In this design, the free-standing grid was replaced by a tungsten layer composed of a matrix of 11x11 extraction gates. Each extraction gate had a circular aperture of 6 µm in diameter. These design changes solved the delamination issues found for the first prototype. Also, for an extraction field of 7 V/µm, an emission current around 0.14 µA per pixel was measured; this value is higher than the 0.08 µA per pixel obtained from the initial FEA prototype at the same extraction field"--Abstract, page iii.

Advisor(s)

Castano Giraldo, Carlos Henry

Committee Member(s)

Lee, Hyoung-Koo
Alajo, Ayodeji Babatunde
Usman, Shoaib
Divan, Ralu

Department(s)

Nuclear Engineering and Radiation Science

Degree Name

Ph. D. in Nuclear Engineering

Publisher

Missouri University of Science and Technology

Publication Date

2014

Pagination

xi, 126 pages

Note about bibliography

Includes bibliographic references (pages 121-125).

Rights

© 2014 Chrystian Mauricio Posada Arbelaez, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Diamond thin films
Field emission
Microfabrication

Thesis Number

T 10859

Electronic OCLC #

953972712

Download

Share

 
COinS