Excitonic Effects in Cd_1—xMn_xSe Quantum Dots and Cd_1—xMn_xTe/ZnTe Quantum Wells

Excitonic properties and dynamics are studied in nanostructure diluted magnetic semiconductors by transient luminescence and nonlinear optical spectroscopies. Quantum dots (QDs) of Cd_1—xMn_xSe show enhanced excitonic magnetic polaron effects with an increased binding energy of 20 meV. Quantum wells (QWs) of the Cd_1—xMn_xTe/ZnTe (x = 0 to 0.2) system display fast dephasing relaxation of the QW exciton with the dephasing time T₂ of 360 to 450 fs, which indicates the fast dephasing process of free excitons in the strained QWs. In the asymmetric double QWs, the tunneling time of carriers through the intermediate barrier is determined as 0.01 to 10⁶ ps for barrier thicknesses of 40 to 320 Å. An enhanced excitonic magnetic polaron binding energy, the rapid dephasing of free excitons and tunneling of carriers are the characteristic properties of the QW excitons in the diluted magnetic semiconductor nanostructures.