Effects of O2, Ar, and H2 gases on the field-emission properties of single-walled and multiwalled carbon nanotubes

We compare the effects Of O-2, Ar, and H-2 gases on the field-emission (FE) properties of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs). We find that H2 and Ar gases do not significantly affect the FE properties of SWNTs or MWNTs. O-2 temporarily reduces the FE current and increases the turn-on voltage of SWNTs. Full recovery of these properties occurs after operation in UHV The higher operating voltages in an O-2 environment cause a permanent decrease of the FE current and an increase in the turn-on field of MWNTs. The ratios of the slopes before and after O-2 exposure are approximately 1.04 and 0.82 for SWNTs and MWNTs, respectively. (C) 2001 American Institute of Physics.