Emission from Mesoscopic-Size Islands Formed in a GaAs/AlAs Double Layer Structure

A. Wysmołeka,b, B. Chwalisza,b, M. Potemskib, R. Stępniewskia, A. Babińskia,b, S. Raymondc and V. Thierry-Miegd aInstitute of Experimental Physics, Warsaw University, Hoża 69, Warsaw, Poland bGrenoble High Magnetic Field Laboratory, MPI/FKF and CNRS, Grenoble, France cInstitute for Microstructural Sciences, NRC, Ottawa, Canada, K1A 0R6 dLaboratoire de Photonique et de Nanostructures, CNRS, 91460 Marcoussis, France

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Received: 10 06 2004

The nature of sharp emission lines which are present in macro-luminescence experiments on a type-II GaAs/AlAs double quantum well structure is discussed. The experiments, which also include micro-lumines- cence measurements, allowed us to conclude that the sharp emission lines observed originate from lateral GaAlAs islands of a fewμm in diameter. They serve as efficient type-I recombination centers for indirect excitons and/or carriers which diffuse in the GaAs/AlAs QW structure and strongly affect the emission processes observed in macro-luminescence experiments. These traps can easily be filled with electron--hole pairs, giving rise to the formation of neutral excitons as well as more complex excitonic molecules. Magneto-luminescence spectra from single islands resemble those observed for natural quantum dots formed in narrow GaAs quantum wells.

DOI: 10.12693/APhysPolA.106.367 PACS numbers: 78.67.De, 78.20.Ls, 71.35.Lk, 73.20.-r, 78.47.+p