Controlling graphene ultrafast hot carrier response from metal-like to semiconductor-like by electrostatic gating

Nano Lett. 2014 Mar 12;14(3):1578-82. doi: 10.1021/nl404826r. Epub 2014 Feb 28.


We investigate the ultrafast terahertz response of electrostatically gated graphene upon optical excitation. We observe that the photoinduced terahertz absorption increases in charge neutral graphene but decreases in highly doped graphene. We show that this transition from semiconductor-like to metal-like response is unique for zero bandgap materials such as graphene. In charge neutral graphene photoexcited hot carriers effectively increase electron and hole densities and increase the conductivity. In highly doped graphene, however, photoexcitation does not change net conducting carrier concentration. Instead, it mainly increases electron scattering rate and reduce the conductivity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.