Optically-Determined Exciton Transport in GaAs Structures

G.D. Gililanda, D.J. Wolfordb, H.P. Hjalmarsonc, M.S. Petrovicb, J. Klemc, T.F. Kuechb, G.A. Northropb and J.A. Bradleyb aEmory University, Physics Dept., Atlanta, GA 30322, USA bIBM T.J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598, USA cSandia National Laboratories, Albuquerque, NM 87185, USA

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We have used an all-optical photoluminescence-imaging technique to measure excitonic transport in three types of GaAs structures in which the excitonic transitions vary from allowed direct-gap excitons to forbidden, doubly-indirect Type-II excitons. We f nd remarkable differences in the transport properties of these excitons. Our studies show that bulk free-exciton transport exhibits an anomalous laser power-dependent diffusivity, whereas quasi-2D interfacial excitons and Type-II cross-interface excitons do not. Additionally, we observe localization of cross-interface excitons at the potential disorder induced by the heterointerface roughness.

DOI: 10.12693/APhysPolA.84.409 PACS numbers: 78.47.+p, 72.80.Ey