Photoluminescence investigations of 2D hole Landau levels in p-type   single Al_{x}Ga_{1-x}As/GaAs heterostructures
  We study the energy structure of two-dimensional holes in p-type single Al_{1-x}Ga_{x}As/GaAs heterojunctions under a perpendicular magnetic field. Photoluminescence measurments with low densities of excitation power reveal rich spectra containing both free and bound-carrier transitions. The experimental results are compared with energies of valence-subband Landau levels calculated using a new numerical procedure and a good agreement is achieved. Additional lines observed in the energy range of free-carrier recombinations are attributed to excitonic transitions. We also consider the role of many-body effects in photoluminescence spectra. 
M. Kubisa, L. Bryja, K. Ryczko, J. Misiewicz, C. Bardot, M. Potemski,   G. Ortner, M. Bayer, A. Forchel, C. B. Sorensen