Binding energy of localized biexcitons in AlGaN-based quantum wells

Abstract

The excitonic optical properties of Al0.60Ga0.40N/Al0.70Ga0.30N multiple quantum wells were studied by photoluminescence (PL) and PL excitation spectroscopies at room temperature. The binding energy of localized biexcitons in quantum wells was evaluated to be 136 meV on the basis of the energy separation between the exciton resonance and the two-photon biexciton resonance. This value was 2.4 times larger than the biexciton binding energy of 56 meV in an Al0.61Ga0.39N ternary alloy epitaxial layer with almost the same aluminum composition as the quantum-well layers. This increase unambiguously resulted from the effect of quantum confinement on biexcitons.