We report observation of the Coulomb blockade effect in a metal-on-tube met
al/multiwall carbon nanotube (MWNT)/metal structure (metal=Ti or Pt/Au). We
find that the tunnel barrier is located in the interface between the MWNT
and the metal electrode, and that the tunnel resistance depends crucially o
n the electrode material. A possible origin of the high contact barrier is
discussed. (C) 2001 American Institute of Physics.