Tunneling and energy transfer in ZnSe-based semimagnetic double quantum wells

An asymmetric double-quantum-well structure has been fabricated by molecular-beam epitaxy, consisting of a semimagnetic (Zn,Cd,Mn)Se and a nonmagnetic (Zn,Cd)Se well, weakly coupled via a ZnSe barrier. Level crossing of the quantum well excitons is accomplished through an external magnetic field. The crossing is accompanied by reverse of the tunneling direction. The tunneling process is of excitonic nature. Besides the very efficient 2-LO-phonon scattering mechanism, indications for a radiationless resonance energy-transfer have been found.