Carbon nanotube based field effect transistors

Carbon nanotube based field effect transistors (CNTFETs) and their relevant phenomena have been studied in this project. Single-wall carbon nanotubes (SWNTs) as the channel of the CNTFETs were placed between source and drain electrodes using AC dielectrophoresis technique. The observed results show that SWNTs are placed between two cross-structured electrodes along the direction of the electric field. The number of aligned SWNTs is determined by the concentration of the SWNT suspension, the processing time and electric field distribution. These experimental phenomena are analyzed theoretically in terms of the dielectrophoresis induced torque and force on the SWNTs. The simulated results suggest that the rotation time for a bundle from a random direction to the electric field direction is much shorter than the translation time. Since both metallic SWNTs (m-SWNTs) and semiconducting SWNTs (s-SWNTs) could bridge the source and drain electrodes simultaneously, the breakdown process was used to burn off the m-SWNTs. The as-prepared CNTFETs show p-type and ambipolar characteristics, depending on the solvents used for dispersing SWNTs. The CNTFETs prepared using isopropyl alcohol (IPA) and water/ sodium dodecyl sulfate (SDS) suspension exhibit ptype behavior. The ON/OFF current ratio is up to 5 10 7