Electronic wavefunctions in asymmetric double quantum well structures studied via spin-flip Raman spectroscopy

Spin-flip Raman spectra have been obtained for two heterostructures, each containing a single CdTe quantum well and a single Cd_1-xMn_xTe quantum well, with barriers of Cd_1-yMn_yTe (y<x). The spectra show a clear sensitivity to the thickness of the central barrier between the two wells. The magnitude of the Raman shifts and the resonance energies help identify the origin of the signals in the structures. When the barrier is broad, two signals are observed, one from each separate well. When the width of the barrier is reduced, a single signal is seen, reflecting the coupling of the electronic states of the two wells. The size of the Raman shifts observed also suggest the presence of a low concentration of donors in the material, which modify the form of the electronic wavefunction in the quantum wells.