Direct View of Hot Carrier Dynamics in Graphene

• DOI: 10.1103/physrevlett.111.027403
• Publication Date: 2013-07-10T16:24:03Z
• Authors: Jens Christian Jo...; Søren Ulstrup; Federico Cilento; Alberto Crepaldi; Michele Zacchigna; Cephise Cacho; I. C. Edmond Turcu; Emma Springate; Felix Fromm; Christian Raidel; Thomas Seyller; Fulvio Parmigiani; Marco Grioni; Philip Hofmann
• Keywords: Thermalisation; Fermi energy

The ultrafast dynamics of excited carriers in graphene is closely linked to the Dirac spectrum and plays a central role for many electronic optoelectronic applications. Harvesting energy from electron-hole pairs, instance, only possible if these pairs can be separated before they lose vibrations, merely heating lattice. While hot carrier could so far accessed indirectly, we here present direct time-resolved view on cone by angle-resolved photoemission (ARPES). This allows us show quasi-instant thermalisation electron gas temperature more than 2000 K; determine density; disentangle subsequent decay into excitations optical phonons acoustic (directly via supercollisions); how presence distribution affects lifetime states below Fermi energy.