Composition dependent dynamics of biexciton localization in AlxGa1-xN mixed crystals

Abstract

We report the localization-dependent dynamics of biexcitons in AlxGa1−xN mixed crystals under exciton resonant excitation at low temperatures. After intense laser excitation, biexcitons rapidly localize into the band-tail states. The formation time of localized biexcitons becomes shorter with increasing Al composition. Both the inhomogeneous linewidth and the binding energy of biexcitons increase with the inhomogeneous linewidth of excitons. The biexciton binding energy is enhanced by the restriction of exciton motion to disordered potentials and the dynamics of stable biexcitons determines the optical spectrum in mixed crystals.