We investigate the relaxation of hot carriers by emission of phonons in bulk Si and Si nanowires (NWs) with an identical atomistic methodology. The phonon scattering is strongly enhanced in NWs. At high excitation energy, the carrier cooling is faster in NWs than in bulk, mainly due to the coupling to surface phonons. Slow relaxation is only noticed for electrons at low energy in the conduction band of thin NWs due to the quantum confinement that lifts the degeneracy of the valleys. This work gives insight into the complexity of the carrier cooling in semiconductor nanostructures.

• Received 25 January 2017
• Revised 5 April 2017

DOI:https://doi.org/10.1103/PhysRevB.95.205401