Neutral and positively charged excitons: A magneto-optical study of a p-doped Cd1-xMnxTe quantum well

We present a systematic study of optical transitions in a modulation doped Cd1-xMnxTe quantum well with variable concentration of the hole gas. Using a semimagnetic semiconductor as the quantum well material allowed us to con trol independently the total hole concentration and its distribution betwee n the two spin subbands (by a small magnetic field). Therefore, in transmis sion experiment we analyze population effects and distinguish the influence of spin-independent effects (screening) from spin-dependent ones (phase-sp ace filling and intensity stealing). The observed variation of the exciton (X) and charged exciton (X+) oscillator strengths can be accounted for assu ming that the influence of phase-space filling is negligible and the variat ion of oscillator strength due to screening is found to be similar for both exciton species. We also show that the X+ dissociation energy significantl y increases with the population of preexisting carriers with the appropriat e spin. [S0163-1829(99)09147-X].