Energy and recombination spectra of free and impurity-bound positive trions in high magnetic fields

Recombination spectra of free and acceptor-bound positive trions in a quasi-two-dimensional hole gas are investigated by the combination of polarization-resolved photoluminescence and transport in high magnetic fields B and the realistic numerics. The whole family of free positive trions (the pair of bright and dark triplets in addition to the well-known singlet) is observed for the first time. Crossing of the singlet and triplet Coulomb energies is found at View the MathML source. Slight decrease of all trion emission energies is observed at View the MathML source, coincident with the formation of a View the MathML source Laughlin hole liquid. For the acceptor-bound trions, weak inter-Landau-level shake-up transitions are identified and explained by the breaking of translational invariance.