Collision broadening of two-dimensional excitons in a GaAs single quantum well

Abstract

The phase relaxation of two-dimensional (2D) heavy-hole excitons in a 12-nm GaAs single quantum well subjected to collisions with either free carriers or incoherent heavy-hole excitons is investigated by time-resolved degenerate four-wave mixing. The homogeneous linewidth corresponding to the phase coherence time reveals a collisional broadening due to exciton-exciton scattering and an 8 times stronger exciton-free carrier scattering. Both scattering processes are enhanced for 2D excitons as compared to 3D excitons.