1. Signatures of Chemical Defects in Carbon Nanotube Electronic Devices Brett Goldsmith Collins Lab Department of Physics and Astronomy

2. A broad look at defects Types of Devices (all CVD SWCNT): pristine nanotube with nearly ballistic conduction Growth defects in unmodified nanotubes Mild oxidation (no missing carbon) Harsh oxidation (missing carbon)

3. Tools to Study CNT Defects Scanning Tunneling Microscopy Ishigashi, PRL. November, 2004 Chemical Labeling Fan, Nature Materials. December, 2005 Scanning Gate Microscopy Bachtold, PRL. June, 2000 Kelvin Force Microscopy Bachtold, PRL. June, 2000 Fan, Nature Materials. December, 2005

4. Scanning Probe Microscopy - KFM Kelvin Force Microscopy (KFM): Records forces between tip and sample Measures Surface Potential Allows indirect measurement of local resistance Source V SD V tip Drain VFVF Source Drain

5. Scanning Probe Microscopy - SGM Scanned Gate Microscopy (SGM): Records current through the nanotube circuit Measures local field sensitivity Shows where the device is “gate sensitive” Source V SD V tip Drain VFVF topography topography + SGM

6. Growth Defects - KFM Ballistic Nanotube Nanotube with Growth Defects

7. Ballistic Nanotube Growth Defects – KFM detail Nanotube with Growth Defects:

8. Growth Defects - SGM topography topography + SGM

9. Defect Creation on Nanotubes WE RE CE Vg Many ways to create defects: Mechanical Chemical Irradiation Electrochemical Jaan Mannik V18.7

10. Basic Effects of Oxidation

11. Weak Oxidation

12. Basic Effects of Strong Oxidation Strong Oxidation

13. Mild Oxidation - SGM topography topography + SGM

14. One SWNT after Progressively Harsh Treatments Surface Potential along as-grown CNT: Surface Potential after mild oxidation: Surface Potential after strong oxidation:

15. Weak Defects - KFM Ballistic Nanotube Mildly Oxidized Nanotube

16. Summary Microscopy techniques such as KFM and SGM show that oxidation and growth defects have similar effects on CNT circuits. Dr. Yuwei Fan Dr. Jaan Mannik Brett Goldsmith Alex Kane Derek Kingrey Bucky Khalap Kevin Loutherback Fatima Alim Yasser Elliasal ACS-PRF