IQIM Postdoctoral and Graduate Student Seminar

Friday December 4, 2015 4:00 PM

Semiconducting-to-metallic Photoconductivity Crossover in Graphene

Speaker: Alex Frenzel, UC San Diego
Location: West Bridge 351 (LIGO Science Conference Room)

Abstract: We investigate the transient photoconductivity of graphene at various gate-tuned carrier densities by optical-pump terahertz-probe spectroscopy. We demonstrate that graphene exhibits semiconducting positive photoconductivity near zero carrier density, which crosses over to metallic negative photo- conductivity at high carrier density. These observations can be accounted for by the interplay between photoinduced changes of both the Drude weight and carrier scattering rate. Our findings provide a complete picture to explain the opposite photoconductivity behavior reported in (undoped) graphene grown epitaxially and (doped) graphene grown by chemical vapor deposition.                                                                                                                                                                                                                                            


Series IQIM Postdoctoral and Graduate Student Seminar Series

Contact: Marcia Brown at 626-395-4013