Donor bound or negatively charged excitons in thin CdTe/Cd1-xMnxTe 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 ((DX)-X-0) or a negatively charged exciton (X-). Comparative experimental study and theoretical analysis of this transition in quantum wells of different thicknesses allowed us to attribute it to the (DX)-X-0 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.