II-VI semiconductor quantum dot quantum wells:: a tight-binding study

We have studied the electronic structure, exciton states and optical spectra of spherical semiconductor quantum dot quantum wells (QDQW's) by means of a symmetry-adapted tight-binding (TB) method. We have investigated two classes of QDQW's: CdS/HgS/CdS, based on a US core which acts as a barrier, with a thin HgS well layer intercalated between the core and a clad layer of CdS. The second class of QDQW's is based on ZnS cores covered with US layers which act in this case as a well. The calculated values of the absorption onset show a good agreement with the experimental data. Large photoluminescence Stokes shifts are also predicted. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.