Magnetic field induced evolution from bulk exciton to 2DEG-free hole luminescence in modulation doped heterojunctions

We studied the evolution of the PL spectra in high mobility wide GaAs/AlGaAs heterojunctions (HJ) at 1.9 K with increasing magnetic field ( B⩽7 T ) that was applied perpendicularly to the HJ interface. For different samples the 2DEG density ranges from (0.7– 3)×10 11 cm −2 , and it can be varied by...

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Bibliographic Details
Published in:Physica. E, Low-dimensional systems & nanostructures Low-dimensional systems & nanostructures, 2002, Vol.12 (1), p.524-527
Main Authors: Ashkinadze, B.M., Voznyy, V., Cohen, E., Ron, Arza, Umansky, V.
Format: Article
Language:English
Subjects:
Excitons
Heterojunctions
Luminescence
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Summary:We studied the evolution of the PL spectra in high mobility wide GaAs/AlGaAs heterojunctions (HJ) at 1.9 K with increasing magnetic field ( B⩽7 T ) that was applied perpendicularly to the HJ interface. For different samples the 2DEG density ranges from (0.7– 3)×10 11 cm −2 , and it can be varied by He–Ne laser illumination due to optical depletion. At B=0, the PL is completely dominated by free exciton recombination in the undoped GaAs layer. For a filling factor ν⩽2 a strong PL transformation is observed: the exciton PL intensity decreases and a low-energy PL due to the 2DEG-free hole recombination sharply appears and quickly gains intensity at the expense of the exciton PL. We propose that this is due to a “condensation” of the bulk excitons on the magnetized 2DEG layer at ν⩽2 where the free exciton dissociates into a 2D-electron and hole.
ISSN:1386-9477
1873-1759
DOI:10.1016/S1386-9477(01)00479-9