Atomic and electronic structure at Au/CdSe interfaces.

By means of plane-wave pseudopotential periodic-supercell density functional theory calculations with a gradient-corrected exchange-correlation functional, we investigated the formation and the electronic structure of thin Au overlayers on CdSe(0001) and CdSe(0001) surfaces. We explored several possible Au/CdSe interfaces, including nonstoichiometric cases in which the very interface layer is mixed, namely, contains atoms of both the metal and the semiconductor. The relative formation energies of the computed model structures indicate that the formation of a very thin Au layer on CdSe surfaces can be epitaxial in the very early deposition stages but only in rather Au-rich conditions. The analysis of the band structures, densities of states, and wave functions for the low-energy interfaces reveals that hybridization occurs between the metal and the semiconductor electron states. This hybridization is confined at the very interface and is not expected to have significant consequences on the plasmonic and excitonic excitations that are appealing for nanotechnology applications of metal-semiconductor nanoparticles.