The 2s exciton in intermediate dimensionality structures

We report the observation of the Is and 2s ground state excitons in small-o ffset superlattices with alternating layers of non-magnetic (ZnSe) and dilu ted magnetic (ZnxMn1-xSe) semiconductors. Due to the large Zeeman splitting of the electron states in ZnMnSe, valence and conduction band offsets in t hese structures can be tuned by external magnetic field over the scale of t ens of meV. Two series of superlattices were investigated, with Mn concentr ations close to 10 and 15 atomic percent, respectively. Each series consist ed of five superlattices with different layer thicknesses. The 2s exciton o f the ground state is observed in ail samples, and exhibits a diamagnetic s hift that is consistent with earlier studies. The ability to determine the energy separation between the Is and 2s exciton states: allows us to analyz e our results in the framework of the fractional dimension analysis, and to extract the values of exciton binding energies for the superlattices from the analysis. (C) 2001 Academic Press.