Spin Coherence and Formation Dynamics of Charged Excitons in CdTe/CdMgZnTe Quantum Well

Abstract

We report on a detailed study of the dynamics of charged and neutral excitons in a p-doped CdTe/CdMgZnTe quantum well by time-resolved photoluminescence under strictly resonant excitation. The 1.5 ps resolution of the experimental set-up allows us to resolve the rise time of the charged exciton photoluminescence after resonant excitation of the neutral exciton. We measure τrise ≈ 13 ps. A fit of the photoluminescence dynamics, which takes into account the different relaxation mechanisms of the charged and neutral excitons, yields the charged exciton formation time. We find 65 ps. In a second part the spin coherence dynamics of the charged and neutral excitons in a transverse applied magnetic field is studied. We show that neither the spin orientation nor the spin coherence of electrons is destroyed by the formation process of charged excitons via exciton states.