Reducing exciton-longitudinal-optical phonon interaction with shrinking ZnO quantum dots

Abstract

The exciton-longitudinal-optical-phonon (LO-phonon) interaction was observed to decrease with reducing ZnO particle size to its exciton Bohr radius (a(B)). The unapparent LO-phonon replicas of free exciton (FX) emission and the smaller FX energy difference between 13 and 300 K reveal decreasing weighting of exciton-LO phonon coupling strength. The diminished Frohlich interaction mainly results from the reducing a(B) with size due to the quantum confinement effect that makes the exciton less polar. (C) 2007 American Institute of Physics.