Combined Exciton-Cyclotron Resonance in Photoluminescence of a Two-Dimensional Hole Gas

A two-dimensional hole gas in an asymmetric GaAs/$Ga_{1-x}Al_{x}As$ quantum well is studied by polarization-resolved photoluminescence in high magnetic fields (up to B = 20 T) and at low temperatures (down to T = 50 mK). In addition to the previously reported dominant emission channels of various free and acceptor-bound trions, the high-energy hole cyclotron replicas of the bound states are now also observed, corresponding to the combined exciton-cyclotron resonance. Identification of different transitions in the rich, multi-peak spectra was possible by the analysis of optical selection rules and comparison of the experimental spectra with realistic numerical calculations.