Unidirectional Exciton Diffusion in Lz-Gradient Quantum Well

By using a J-photoluminescence (PL) detecting system, spatial diffusion and propagation processes of high density excitons were investigated in an Lz-gradient GaAs quantum well (QW) structure, in which the QW-excitons experience driving force due to an energy gradient of the Lz-depending confined energies of electrons and holes. We found asymmetric distribution of the PL intensity of the QW-excitons owing to the unidirectional exciton propagation to the driving force direction. PACS: 66.30.Pa; 71.35.Lk; 71.35.-y; 78.67.De; 81.07.St.