A series of emission current measurements were taken from various types of multiwalled carbon nanotube (MWCNT) films in order to examine their stability for electron field emission. We found that the MWCNTs films grown by the catalytic thermal chemical vapor deposition (CVD) method exhibited much improved emission stability as compared to MWCNT films grown by the plasma-enhanced CVD (PECVD) method. We explain this difference of performance by referring to the graphitic order of these MWCNTs as detected by transmission electron microscopy and Raman spectroscopy. Results indicate that MWCNTs with high-order tubular structures demonstrate stable electron field emission. The best performing sample exhibits a constant current degradation of ̈3% per hour at an emission current density of ̈1 mJ/cm2.
Category: 2006
Growth of adhesive cubic phase boron nitride films without argon ion bombardment
Previously, in situ bombardment of massive ions (Ar+, Kr+, etc.) was considered to be necessary for the formation of c-BN films. Because of
the accumulated stress, bombardment of massive ions has led to the formation of c-BN films with poor adhesion. Here we show that c-BN films
can be grown without involving bombardment of massive ions. This is achieved by using plasma-assisted pulsed-laser deposition (PLD) in pure
N2 RF plasma. Furthermore, we show that c-BN films can be grown in a vacuum ( ̈105 mbar during growth) by PLD without auxiliary ion
source. We show that these are possible at a reduced deposition rate. Energetic growth species initiated by PLD and the pure N2 plasma is
sufficient to form adhesive c-BN films at moderate deposition rate as long as the energy transfer rate per growth species is sufficient.
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