The effect of a magnetic field on the graphitization of carbon nanotubes and its application in field emission

A low-temperature thermal chemical vapor deposition with an applied external magnetic field was used to grow carbon nanotubes (CNTs) on the bottom of a triode-type glass substrate. The Raman spectra reveal the graphitization of CNTs synthesized with different external magnetic fields. The magnetic field plays an important role in the growth of CNTs at low temperature (the ID/IG ratios decreased from 0.774 to 0.579, 0.426 and 0.305, for the samples with different magnetic forces of 0, 6.8, 12 and 13 kG, respectively), which enhances the crystalline structure of CNTs and improves their field emission properties (the anode current increased from 0.01 to 180, 290 and 420 μA with different applied external magnetic fields) for a triode-type field emission display application.

The images of field emission CNT-based triode-type panel on a red, green, and blue color phosphor, which obtained a uniform emission image with high stability. These images were taken at the gate and anode electrode biases of 80 V and 1.8 kV, with a duty ratio of 1/120 and a frequency of 100 Hz, as shown in Figures (a) and (b). By decreasing the frequency from 100 to 10 Hz, the anode plate exhibited a white color image, as shown in Figure (c).Figure optionsDownload as PowerPoint slideHighlights
► The magnetic field enhances the graphitized structure of CNTs synthesized at low temperature.
► CNTs synthesized with a high magnetic field grow a better crystalline structure and better field emission effect.
► CNT directly grow on the glass substrate without any glass deformation.
► The CNT cathode did not need any surface treatment (surface activation) for field emission application.
► Obtained a uniform field emission performance with high stability.