Increase of the e1-hh3 exciton oscillator strength in quantum-well structures under the type-I–type-II transition

The drastic transformation of the exciton spectra induced by the type-I–type-II transition in the quantum-well (QW) band alignment is revealed theoretically and observed in the magnetoreflection spectra of the CdTe/(Cd,Mn)Te QW structure. The oscillator strength of the e1-hh3 exciton is found to increase in the course of the magnetic-field-induced type-I–type-II transition, while the ground e1-hh1 state oscillator strength decreases. We conclude that the e1-hh3 exciton remains spatially direct in a well-pronounced type-II QW, contrary to the e1-hh1 state, which becomes spatially indirect.