We explore the electric-field effect of carbon nanotubes (NTs) in electrolytes. Due to the large gate capacitance, Fermi energy 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 hole doped in air with E_F ? 0.3-0.5 eV, corresponding to a doping level of ? 10^{13} cm^{-2}. Hole-doping increases in the electrolyte. This hole doping (oxidation) is most likely caused by the adsorption of oxygen in air and cations in the electrolyte.
@article{arxiv.cond-mat/0009171,
title = {The Electrochemical Carbon Nanotube Field-Effect Transistor},
author = {M. Krueger and M. R. Buitelaar and T. Nussbaumer and C. Schoenenberger and L. Forro},
journal= {arXiv preprint arXiv:cond-mat/0009171},
year = {2016}
}