1. Electrical Properties of Defects in Carbon Nanotubes Brett Goldsmith UC Irvine Department of Physics and Astronomy Collins Group

2. SPM Studies of Nanotubes There have been a number of studies to characterize the frequency and effects of defects in nanotubes. Some unanswered questions still remain: –Is gate dependence only based on band structure? –Are high resistance devices always dominated by contact effects? Freitag et al, PRL 89 (21) 2002

3. source electrodedrain electrode nanotube Insulator Gate Nanotube Transistors

4. Scanned Gate Microscopy Setup Source V SD VGVG V tip Drain 1 M apply AC+DC back gate lock in on AC current here apply DC tip gate

5. SGM – Semiconducting Nanotube 3 V DC back Gate

6. SGM – Gate Dependance 5 V DC back Gate

7. SGM – Metallic Tube

8. Kelvin Probe Microscopy Source V SD VGVG V tip Drain 1 M DC voltage across nanotube AC voltage between tip and entire sample

9. Local Voltage Drops 900 kΩ 570 kΩ ? ?

10. Changing the Voltage Profile 2V 3V

11. Combining SGM and KFM

12. Summary metallic nanotubes can have local gate dependence gate sensitive regions correspond to points of local voltage drops Dr. Phil Collins Dr. Yuwei Fan Nathan Emmott Derek Kingrey Alex Kane Bucky Khalap Jorge Guerra Kevin Loutherback ACS-PRF