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In this study, thermal chemical vapor deposition (CVD) was utilized to grow carbon nanotubes (CNTs).Silane was the main source for carbon, and argon was used as the carrier gas.CNTs were synthesized from carbon atoms obtained from catalytic thermal decomposition of silane.H2 gas and Ar gas plasma treatment was utilized for carbon nanotubes (CNTs).Scanning electron microscopy ( SEM ) image was used to observe the surface morphology and sidewall structure of CNTs, and Raman spectroscopy was employed to investigate the structural changes caused by plasma treatments.It was found that the CNTs treated with both non-reactive Ar and reactive H2 plasmas have a higher density of amorphous carbon and a smaller average diameter compared with that of untreated CNTs reflecting the etching effects of plasma treatments.In addition, higher emission currents and lower turnon electric fields were also observed for the CNTs treated with Ar and H2 plasmas compared with that of untreated CNTs.As expected, reactive plasma treatment has a more pronounced effect on the surface morphology and field emission characteristics than non-reactive plasma treatment.In particular, a huge increase in emission current (three to four orders of magnitude at high electric fields) and a substantial lower turn-on electric field were found for the CNTs treated with H2 plasma.This huge increase in the emitted current for the CNTs after H2 plasma treatment is primarily caused by the increase in the density of field emission sites which is resulted from the change of surface morphology and the - CHx nanoparticles redeposited on the CNTs.