The study on field emission properties of different carbon nanotubes deposited by electrophoresis

Two different carbon nanotubes (CNTs) were synthesized by thermal chemical vapor deposition (CVD) system through two different apparatuses. Uniform deposition of CNTs on glass substrate was observed through optimizing parameters in the process of electrophoresis by scanning electron microscopy (SEM). The field emission properties were tested in the diode-type construction with the cathode-anode gap of 170 mum. The result showed CNTs synthesized by pyrolysis of iron(II) phthalocyanine (FeC₃₂N₈H16) showed much better field emission properties such as lower turn-on field (defined at a current of 10 mu A/cm²) of 2.35 V/mum. On the other hand, even the field reached 5.29 V/mu m, only 8.7 mu A/cm² emission current density was obtained from the CNTs fabricated using acetylene (C₂H₂) as the carbon source. These differences result from the structure of CNTs such as radius and length.