Date of Award

Fall 1997

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Sacharia Albin

Committee Member

Linda L. Vahala

Committee Member

Karl Schoenbach

Call Number for Print

Special Collections LD4331.E55 C56

Abstract

Typical field emitters consist of sharp metal tips which usually have a short life due to erosion and contamination. To improve the performance of regular field emitters, diamond can be placed on the emitter tip. This is done by selectively growing diamond on tungsten tips using chemical vapor deposition (CVD) processing. Diamond exhibits negative electron affinity, so that electrons will be emitted by properly biasing the tip.

To obtain single crystal growth right at the tip, a cantilever controlled nucleation method was developed which worked better than other methods. Surface preparation was also important to the growth process. An oxide layer was used to prevent random diamond growth and to prevent the tungsten from becoming brittle. Crystal characteristics were observed using scanning electron microscopy (SEM) and Raman spectroscopy. Size, quality and orientation of the diamond crystals varied with CVD process parameters. Higher temperatures and pressures yielded larger crystals with generally better quality, The (111) orientation was predominant at 40 Torr and higher temperatures, while the (100) orientation was favored at 60 Torr and higher temperatures. Higher amounts of methane yielded larger crystals, but the quality of the diamond was poor. Optimum conditions were determined to fabricate a diamond tip on tungsten.

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DOI

10.25777/rg9q-7019

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