MAGNETOOPTICAL STUDIES OF THE TYPE-I TYPE-II CROSSOVER AND BAND-OFFSET IN ZNTE ZN1-2MNXTE SUPERLATTICES IN MAGNETIC-FIELDS UP TO 45 T/

We report measurements of magnetoreflectivity in ZnTe/Zn1-xMnxTe super lattices with varying well width in magnetic fields up to 45 T. From a n analysis of the Zeeman splitting, we investigate the change of band alignment with field and the band offset ratio. A crossing of the is e xciton transitions from the ZnTe buffer layer and the 1s heavy hole si gma(+) exciton of the superlattice is observed, providing unambiguous evidence of a band alignment change from type I to type II. The excito nic energy levels for both type-I and type-II band structure are calcu lated using a variational method. This model fits the experimental dat a very well at high fields for both sigma(+) and sigma(-) transitions and predicts that the type-I/type-II crossover occurs at 2-3 T. Also b y fitting the sigma(+) transition energy as a function of held a condu ction band offset ratio of Delta E(c)/Delta E(g)=0.72+/-0.04 is deduce d.