Abstract
We present a microscopic study on the impact of doping on the carrier dynamics in graphene, in particular focusing on its influence on the technologically relevant carrier multiplication in realistic, doped graphene samples. Treating the time- and momentum-resolved carrier-light, carrier-carrier, and carrier-phonon interactions on the same microscopic footing, the appearance of Auger-induced carrier multiplication up to a Fermi level of 300 meV is revealed. Furthermore, we show that doping favors the so-called hot carrier multiplication occurring within one band. Our results are directly compared to recent time-resolved ARPES measurements and exhibit an excellent agreement on the temporal evolution of the hot carrier multiplication for n- and p-doped graphene. The gained insights shed light on the ultrafast carrier dynamics in realistic, doped graphene samples.
Highlights
We present a microscopic study on the impact of doping on the carrier dynamics in graphene, in particular focusing on its influence on the technologically relevant carrier multiplication in realistic, doped graphene samples
We show that doping favors the so-called hot carrier multiplication occurring within one band
We discuss how the doping-induced symmetry breaking between electrons in the conduction band and holes in the valence band influences the dynamics of optically excited charge carriers in realistic doped graphene samples
Summary
Faris Kadi[1], Torben Winzer[1], Andreas Knorr1 & Ermin Malic[2] received: 06 September 2015 accepted: 21 October 2015. A number of theoretical and experimental studies has been performed aiming at a thorough understanding of the carrier relaxation dynamics in optically excited graphene[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15] Most of these studies focus on the ultrafast Coulomb- and phonon-induced carrier dynamics without considering the influence of doping in the investigated graphene samples. The focus lies in particular on the impact of a finite Fermi level on the appearance of the technologically relevant carrier multiplication[16,17,18,19,20,21,22,23,24,25,26,27] This interesting ultrafast phenomenon is related to the linear electronic band structure of graphene opening up the possibility of efficient Coulomb-induced Auger processes. Since these hot carriers are crucial for many technological applications, the appearance of hCM is of technological relevance
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