title: pH-dependent electron-transport properties of carbon nanotubes.
abstract: Carbon nanotube electrochemical transistors integrated with microfluidic channels are utilized to examine the effects of aqueous electrolyte solutions on the electron-transport properties of single isolated carbon nanotubes. In particular, pH and concentration of supporting inert electrolytes are examined. A systematic threshold voltage shift with pH is observed while the transconductance and subthreshold swing remain independent of pH and concentration. Decreasing pH leads to a negative shift of the threshold voltage, indicating that protonation does not lead to hole doping. Changing the type of contact metal does not alter the observed pH response. The pH-dependent charging of SiO2 substrate is ruled out as the origin based on measurements with suspended nanotube transistors. Increasing the ionic strength leads to reduced pH response. Contributions from possible surface chargeable chemical groups are considered.
authors.affiliation: Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Ju Hee
authors.initials: JH
authors.lastname: Back
authors.forename: Moonsub
authors.initials: M
authors.lastname: Shim
mesh_terms: D004553:Electric Conductivity; D004563:Electrochemistry; D004573:Electrolytes / Q000737:chemistry*; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000737:chemistry; D012666:Semiconductors; D012822:Silicon Dioxide / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D014173:Transistors, Electronic
chemical_list: D004573:Electrolytes; D037742:Nanotubes, Carbon; D012996:Solutions; D011189:Potassium Chloride; D012822:Silicon Dioxide