High field transport properties of a bilayer graphene

Hot carrier relaxation of Dirac fermions in bilayer epitaxial graphene

“…6 (Figure 7 inset). We emphasize that this n −1.5 e dependence in bilayer graphene, due to its parabolic dispersion relation at low energies [11], is very different from the n −0.5 e dependence for monolayer graphene which has been theoretically predicted [14] and already experimentally observed [6]. As a comparison, the carrier density dependence of α in monolayer graphene is plotted in the same figure. Below the crossing point corresponding to a carrier density of approximately 1.86 × 10 12 cm −2 and at carrier temperatures between 1.4 K and 100 K, hot carriers in bilayer graphene will be able to lose energy faster than those in monolayer and vice versa.…”

“…So far, no theoretical extension of the "supercollisions" to bilayer graphene has been reported and our results show no evidence of the transition to a T 3 dependence as observed in monolayer graphene. Another possible cooling mechanism to retain the energy loss rate increasing as T 4 in a substrate supported bilayer graphene sample could be the interaction between hot electrons and surface polar phonons (SPPs) [11][12][13], combined with hot phonon effects which occur when the hot phonon decay rate is not as fast as the phonon emission rate. However, theoretical calculations based on a SiC substrate suggest the contribution from SPPs can only be clearly observed for electron temperatures higher than 100 K [13], due to the relatively low dielectric constant and high surface polar phonon energies of SiC, compared with substrates such as HfO 2 .…”

“…Very recently, energy loss rates for hot carriers in bilayer graphene have been theoretically explored taking into account the interactions of electrons with acoustic and surface polar phonons as well as hot phonon effects [11][12][13], but to date this has yet to be studied in significant detail experimentally.…”

The role of vector potential coupling in the hot electron cooling power in bilayer graphene at low temperature

“…We suggest, in order to see the VP coupling contribution to the hot electron cooling power, measurements need to be made over the large range of n s covering the cross over region.. It is to be noted that the BG regime studies in conventional in 2DEG [22],TMDs [23] and bilayer graphene (unscreened DP coupling) [18], with the parabolic dispersion of electron energy, show n s -3/2 dependence. But the n s -1/2 dependence of VP coupling in BLG, with the same parabolic dispersion for electrons, is due to the explicit dependence of its matrix element on electron energy (see Eq.…”

Electron cooling in three-dimensional Dirac fermion systems at low temperature: Effect of screening

“…Electron heating by photons finds potential applications in bolometry and calorimetry. Hot electron cooling is extensively studied, theoretically and experimentally, in bulk semiconductors , conventional two‐dimensional electron gas (2DEG) of low‐dimensional semiconductor heterostructures , graphene and in monolayer MoS 2 . Also, there exists a study of cooling of hot carriers on the surface of topological insulator Bi 2 Se 3 .…”