Special Kavli Seminar

Thursday, November 15, 2018 | 2:00pm - 3:00pm
Location: 775 Tan Hall

Carbon Nanotubes, Who Knew Doping Could be so Complicated (and Why You Should Care)

Professor Tobias Hertel

Institute of Physical and Theoretical Chemistry, Julius-Maximilians University Würzburg, Germany

Doping of nanoscale semiconductors is often critical for providing electronic and photonic device functionality. However, our understanding and control of the underlying charge transfer processes just as often lack the sophistication and finesse required for these mate-rials to become technologically viable. Here we discuss recent insights into the doping of semiconducting carbon nanotubes (s-SWNTs) using a variety of optical spectroscopies and doping schemes, from femtosecond time-resolved pump-probe studies of redox doped s-SWNTs to photoluminescence microscopy of individual, electrochemically doped nano-tubes. The experiments now allow a quantitative determination of doping levels in carbon nanotubes using simple absorbance measurements. We also discuss a wealth of infor-mation that such experiments may reveal about the nature of exciton and trion photophys-ics in low-dimensional semiconductors. In addition our findings point toward more funda-mental challenges with providing and controlling excess carriers in one- or two-dimensional atomically thin systems due to notoriously weak screening and the resulting sensitivity to external perturbations.

Tobias Hertel is chaired Professor at the Julius-Maximilians University in Wuerzburg, Ger-many. In 1995 he received his Ph.D. degree in Physical Chemistry from the Free University Berlin for research done with Gerhard Ertl at the Fritz-Haber-Institute. After postdoctoral work at IBM’s T.J. Watson Research Center with Phaedon Avouris, he completed his Habili-tation in experimental physics at the Free University of Berlin and in 2004 accepted the of-fer for an Associate Professor position at Vanderbilt University. In 2008 he returned to Germany where he now holds the Chair for Physical Chemistry in the Department of Chem-istry and Pharmacy along with an Adjunct Professorship in the Department of Physics of the JMU Wuerzburg.