Hot electron cooling by acoustic phonons in graphene.
Phys Rev Lett
; 109(5): 056805, 2012 Aug 03.
Article
in En
| MEDLINE
| ID: mdl-23006198
ABSTRACT
We have investigated the energy loss of hot electrons in metallic graphene by means of GHz noise thermometry at liquid helium temperature. We observe the electronic temperature T â V at low bias in agreement with the heat diffusion to the leads described by the Wiedemann-Franz law. We report on T â âV behavior at high bias, which corresponds to a T(4) dependence of the cooling power. This is the signature of a 2D acoustic phonon cooling mechanism. From a heat equation analysis of the two regimes we extract accurate values of the electron-acoustic phonon coupling constant Σ in monolayer graphene. Our measurements point to an important effect of lattice disorder in the reduction of Σ, not yet considered by theory. Moreover, our study provides a strong and firm support to the rising field of graphene bolometric detectors.