Optically detected heavy- and light-hole anti-crossing in GaAs quantum wells under pulsed magnetic fields

摘要

We report magneto-photoluminescence studies of two undoped GaAs-Al_(0.3)Ga_(0.7)As single quantum well (SQW) samples (120 and 60 A) in pulsed magnetic fields up to ～65 T. Both samples exhibit exciton transitions due to the ground-state (1s) electron-heavy-hole recombination which undergoes diamagnetic energy shifts at low fields and has a liner dependence at high fields. The 120 A SQW shows the electron-light-hole exciton transition at zero magnetic field. However at about 30 T, the electron-heavy-hole and the electron-light-hole transitions intersect and show an anti-crossing behavior. The 60 A SQW shows a similar behavior but the splitting between the heavy- and light-hole excitons can only be observed in the anti-crossing region at about 35 T. The results indicate that the valence band mixing plays a significant role at high magnetic fields.