The trion spin-singlet and -triplet states in ZnSe single quantum wells

The polarization-dependent photoluminescence of the negatively charged trio n is investigated for ZnSe single quantum wells with varying quantum well t hickness between 5 and 20nm and barrier heights ranging from 30 to 200 meV under application of magnetic fields up to 10 T perpendicular to the quantu m well plane. A strong increase of the trion binding energy with decreasing quantum well thickness from about 2.5 to 7 meV is observed. For the trion spin-singlet state the stabilization with increasing magnetic field is foun d to be negligible. Under high magnetic fields (B > 6 T) a shoulder emerges on the low-energy side of the 1 s heavy-hole exciton resonance which is at tributed to the excited trion spin-triplet state becoming stabilized in hig h magnetic fields. (C) 2000 Elsevier Science B.V. All rights reserved.