Energy Relaxation of Hot Dirac Fermions in Graphene


We develop a theory for the energy relaxation of hot Dirac fermions in graphene. We obtain a generic expression for the energy relaxation rate due to electron-phonon interaction and calculate the power loss due to both optical and acoustic phonon emission as a function of electron temperature TeT_{\mathrm{e}} and density nn. We find an intrinsic power loss weakly dependent on carrier density and non-vanishing at the Dirac point n=0n = 0, originating from interband electron-optical phonon scattering by the intrinsic electrons in the graphene valence band. We obtain the total power loss per carrier ∼10βˆ’12βˆ’10βˆ’7W\sim 10^{-12} - 10^{-7} \mathrm{W} within the range of electron temperatures ∼20βˆ’1000K\sim 20 - 1000 \mathrm{K}. We find optical (acoustic) phonon emission to dominate the energy loss for Te>(<)200βˆ’300KT_{\mathrm{e}} > (<) 200-300 \mathrm{K} in the density range n=1011βˆ’1013cmβˆ’2n = 10^{11}-10^{13} \mathrm{cm}^{-2}.Comment: 5 page

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    Last time updated on 03/01/2020