Abstract
The authors report pH -dependent conductance behaviors of single-walled carbon nanotube (SWCNT) multilayer thin-film sensors. SWCNTs are functionalized with carboxylic groups, and layer-by-layer assembled alternatively with polycation, polydiallyldimethyammonium chloride on the microfabricated metal electrodes. Current-voltage (I-V) characteristics show that the conductance of SWCNT multilayer thin-film sensors decreases with increase of pH values. On the other hand, the multilayer resistors with polymethylmethacrylate (PMMA) as a passivation layer demonstrate the increasing conductance with pH, opposite to the case of the absence of PMMA layer. The conductance change in the absence of PMMA attributes to doping/undoping of holes as charge carriers by molecular protonation/deprotonation of p -type semiconducting SWCNTs. With PMMA layer, concentration gradient of hydrogen ions on the dielectric forms the gate bias voltage, which changes the conductance of underlying semiconducting SWCNT layer. Each pH -dependent behavior has versatile applications for chemical and biological detections.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 842-848 |
| Number of pages | 7 |
| Journal | Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures |
| Volume | 27 |
| Issue number | 2 |
| DOIs | |
| State | Published - 2009 |
Bibliographical note
Funding Information:This work was partially supported by the DARPA M/NEMS Science and Technology Fundamental Research Program through the Micro/Nano Fluidic Fundamental Focus (MF3) Center. The authors would like to thank the Nanofabrication Center and Characterization Facility at the University of Minnesota for the help with fabrication and characterization.