We explore the electric-field effect of carbon nanotubes (NTs) in electroly
tes. Due to the large gate capacitance, Fermi energy (E-F) shifts of order
+/-1 V can be induced, enabling to tune NTs from p to n-type. Consequently,
large resistance changes are measured. At zero gate voltage, the NTs are h
ole-doped in air with parallel toE(F)parallel to approximate to 0.3-0.5 eV,
corresponding to a doping level of approximate to 10(13) cm(-2). Hole-dopi
ng increases in the electrolyte. (C) 2001 American Institute of Physics.