FIELD ELECTRON EMISSION AT INSULATOR COATED TIPS
- Details
- Category: Physics
- Published: Thursday, 10 May 2012 03:00
- Written by KhalilOmarMussa
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Abstract
Field Electron Emissin from Insulator Coated Tips
KhalilOmarMussa
Mu’tahUniversity, 2010
The present thesis deals with the emission of electrons from the surface of metals into vacuum due to a strong electric field applied. This process is usually dubbed cold field electron emission (CFE). It is an important process having a number of technical applications at present as well as further ones being proposed or in development right now. The applications include emitters within electron microscopes and field emission displays.
The research work carried out addresses the long term stability of coated electron emitter tips. For this purpose, a number of coated tungsten tips have been retested, which were manufactured and initially examined 10 to
15 years ago. During this time, the respective tips have been stored under standard atmosphere conditions, which is a relatively rough environment for such sharp needles of about 100 nm apex radius.
The measurements performed include the I–V characteristics, emission images, chemical analysis as well as scanning electron micrographs. The results are compared to those obtained before as well as to measurements carried out on clean tungsten tips manufactured as part of this work.
Even though the results show a certain decay of the tips in general as well as the structure of the coating in particular, as all tips were still functional. Thus one can draw optimistic conclusions as to the expectable lifetime of technical equipment applying CFE technology.