First-principles investigation of the structure and electronic properties of CdS/CdSe/CdS and CdS/CdTe/CdS quantum wells using a slab approximation

The structure and electronic properties of CdS, CdSe, and CdTe thin films and multilayer CdS/CdSe/CdS and CdS/CdTe/CdS heterostructures simulating quantum wells of these compositions are performed using density functional theory and a slab approximation. Various crystal modifications and various crystallographic surfaces of the specified compounds are considered. In the calculations, the GGA approximation for the exchange-correlation functional (PW91) and ultrasoft pseudopotentials are used. For the systems in study, the work functions are calculated for various surfaces. The calculated structural data are in good agreement with experiments. The calculated surface reconstruction can be qualitatively described as an inward displacement of cadmium atoms into the surface crystal layer and an outward displacement of chalcogen atoms. The calculated surface energies indicate that the (110) surface formation energy is lower than the (100) surface formation energy. The calculated work functions decrease in the sequence CdS > CdSe > CdTe, while the calculated work functions for multilayer structures are between the corresponding values for the pure components of the structure. © 2010 Pleiades Publishing, Ltd.