Two-dimensional electron bound hole photoluminescence in GaAs in perpendicular magnetic fields

Schuster, J. and Kim, T.Y. and Batke, E. and Reuter, D. and Wieck, A.D.

Volume: 35 Pages:
DOI: 10.1088/1361-6641/ab89e1
Published: 2020

The photoluminescence of quasi two-dimensional (2D) electrons in modulation doped Al x Ga1 - x As-GaAs single heterostructure recombining with bound holes was studied at liquid helium temperatures in magnetic fields up to 9 T. Luminescence contributions from the ground and a weakly populated first excited 2D subband were observed as well as bulk-like contributions from the GaAs buffer. The 2D subband and the bulk signals are linked and oscillate with the magnetic field strength. It is not the filling factor that rules but the alignment of the two subband Landau-ladders paired with intersubband scattering that drives an oscillatory behavior of the subband populations. Asymmetric Landau-level transition line shapes indicate a perturbed 2D electron system. We performed a detailed analyses of Landau-level dependent line strengths, positions and half widths and compared the experiment with calculations of subband energies and transition matrix elements. The total electron density is not fixed in our experiment but decreases with magnetic field strength. This might indicate that the 2D system exchanges electrons with a reservoir and/or that the correlation between radiative and nonradiative recombination channels vary strongly with the magnetic field strength. © 2020 IOP Publishing Ltd.

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