Temperature dependence of interface barrier height change as implicated by field emission studies of aligned-multiwall carbon nanotubes

We have observed that the change of field emission currents of multiwalled nanotube (MWNT) is not sensitive but detectable to temperature variation within the range from 300 K to 20 K. However, the characteristic curve cannot be congruently fitted by Fowler-Nordheim (FN) theory. Assuming a semiconducting amorphous carbon dot grown on the tube end, the dominated field emission mechanism will be the thermal electron tunneling caused by the high aspect ratio of the tube. This analysis conclusively addresses that the electron affinity and the energy gap of the caps are not changed while the interface barrier height increases as temperature increases. (C) 2003 Elsevier Science B.V. All rights reserved.