Magneto-optical study of ZnSe/(Zn,Mn)Se and ZnSe/(Zn,Cd,Mn)Se quantum well structures and superlattices

Abstract

Quantum well structures with semimagnetic barriers, ZnSe/( Zn, Mn) Se, or semimagnetic wells, ( Zn, Cd, Mn) Se/ ZnSe, are studied by luminescence and reflection spectroscopy in an external magnetic field up to 7.5 T.A. unique offset dependence on the manganese concentration and a type conversion of the ZnSe/( Zn, Mn) Se heterostructures due to the giant Zeeman splitting of the barriers are found. In the ( Zn, Cd, Mn) Se/ ZnSe structures, a strong reduced energy transfer from the exciton states to the Mn internal transition was found, which is further suppressed by an increasing magnetic field. Therefore (Zn,Cd,Mn)Se quantum wells can be proposed to be suitable and effective for tuneable blue-green laser devices in an external magnetic field. The field dependent energy splitting both of well and barrier excitons are significantly anisotropic with respect to the orientation of the magnetic field B parallel or perpendicular to the growth axis. This magneto-optical anisotropy can be explained by the mixing of the heavy and light hole states in the framework of a multi-band envelope-function approximation.