Ms. Mousa, INFLUENCE OF THE APPLIED ELECTRIC-FIELD AND GAS ON THE ENERGY-SPECTRAOF ELECTRONS EMITTED FROM CARBON-FIBER MICROEMITTERS, Ultramicroscopy, 73(1-4), 1998, pp. 23-30
Electron emission from carbon fibre field emission source presented an
inherent instability in the intensity of the emission spot in additio
n to current fluctuations. In this study, techniques were developed to
obtain the best stabilization clearly demonstrating that the intensit
y fluctuations can be eliminated. Chart recorder traces and slow scans
of optically monitored screen signals, that were recorded before and
after treatment of the tip at various temperatures and for different p
eriods are presented. The lifetime measurements of this cathode were r
ecorded over a long period of time. This showed that noise is consider
ably smaller than that encountered with untreated tip. Stable emission
currents permitted obtaining the energy distributions that had single
peaks. The spectral shift from the Fermi level was analyzed and was s
hown to be a function of the emission current. After the initial treat
ment, the emission behavior showed no variation between heated and non
-heated tips. The tip profile was examined using electron microscopy t
echniques. The influence of various residual gases on the emission cha
racteristics was investigated. These gases, and in particular oxygen,
produced no significant variation in the magnitude of the emission cur
rent or its stability. These and other properties of carbon fibre emit
ters have been interpreted in terms of a hot-electron emission mechani
sm. (C) 1998 Elsevier Science B.V. All rights reserved.