Hot electron energy relaxation in a semiconducting armchair graphene nanoribbon

We calculate the hot electron energy relaxation P due to acoustic–phonon scattering via deformation potential coupling in an armchair graphene nanoribbon (AGNR). Its dependence on electron temperature Te, Fermi energy Ef (linear electron concentration nl) and width W of AGNR is investigated. At low Te, P is found to be exponentially suppressed contrary to the power laws in graphene and conventional semiconductor nanostructures. This gradually changes to sublinear behavior for an about Te>100 K contrary to conventional P∼Te. P shows strong dependence on Ef and nl and it decreases with the increasing Ef and nl at low Te. At a constant nl, P varies approximately as W−s with s∼2–3. A weak dependence of s on Te and nl is observed. We point out that the low Te study of P, as it is independent of all non-acoustic phonon scattering mechanisms, could be used to determine the accurate value of acoustic–phonon deformation potential coupling constant in graphene about which there is still uncertainty.