Donor bound or negatively charged excitons in thin ${\mathrm{C}\mathrm{d}\mathrm{T}\mathrm{e}/\mathrm{C}\mathrm{d}}_{1-x}{\mathrm{Mn}}_x\mathrm{Te}$ quantum wells

Magnetophotoluminescence spectroscopy of unintentionally doped thin CdTe/(Cd,Mn)Te single and double quantum wells (QW’s) revealed a pronounced excitonic transition that can be associated with either an exciton bound to a neutral donor ${(D}^{0}X)$ or a negatively charged exciton ${(X}^{-}).\mathrm{}$ Comparative experimental study and theoretical analysis of this transition in quantum wells of different thicknesses allowed us to attribute it to the $D^{0}X$ complex in a single QW and to the $X^{-}$ state in the double QW. A record $X^{-}$ binding energy of 3.7 meV has been detected. The double QW structure was shown to be favorable for the formation of $X^{-}$ in the wide well due to the efficient interwell electron tunneling.