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The concept of time-dependent overlap between Wannier functions is introduced. The proposed tome-dependent overlap coefficient and results obtained could aid in the study and design of new electronic devices.

We report a numerical study of the effect of interface alloying and band alignment on the Auger recombination processes of core/shell nanocrystals. Smooth interfaces are found to suppress Auger recombination, the strength of the suppression being very sensitive to the core size. The use of type-II structures constitutes an additional source of suppression, especially when the shell confines electrons rather than holes. We show that 'magic' sizes leading to negligible Auger recombination [Cragg and Efros, Nano Letters 10, 313 (2010)] should be easier to realize experimentally in nanocrystals with extended interface alloying and wide bandgap. [ABSTRACT FROM AUTHOR]

We propose a simplified and computationally feasible model accounting for the dielectric confinement in arbitrarily shaped many-electron quantum dots, within the local spin density approximation. The model yields quite a good agreement with full configuration interaction calculations including exact dielectric confinement. The model is used to study the influence of the dielectric confinement on the electronic charge distribution of elongated quantum dots in the low density regime. [ABSTRACT FROM AUTHOR]

Delocalized image surface states in free-standing hollow silica nanospheres populated with one or two electrons or an exciton are theoretically predicted for a wide range of internal radii and shell thicknesses. The driving force building up these surface states is the image self-polarization potential originating from the dielectric mismatch between the nanoshell and the surrounding air. The surface states are localized in a spherical crown beyond the nanoshell border. The transition from volume to surface state will then have to overcome the spatial confining potential barrier of the nanoshell. Owing to the different spatial confining barriers of electrons and holes in the silica nanoshell, electron but no hole density can be concentrated in surface distributions. The self-polarization potential looks like a double well potential, each well located just beyond the nanoshell border, with the internal well deeper than the external one, so that an excess carrier is attracted more strongly by the inner interface. This leads the electron density of a surface state to be located mainly in the internal surface of the hollow nanosphere. The shorter the inner nanoshell radius is, the stronger the binding of the excess electron to the surface will be. The volume/surface ground state phase diagrams of the one-electron, two-electron, and exciton systems have been calculated. All three diagrams are quite similar, thus revealing the monoelectronic character of the driving force for the transition from volume to surface states. [ABSTRACT FROM AUTHOR]

The influence of a thin AlAs layer (1 nm) located at different positions inside a GaAs matrix on the electronic states of nearby deposited InAs quantum dots is theoretically investigated. Calculations are performed within the three-dimensional one-band effective mass model including mass dependence on energy and position. In order to provide a realistic description of the wave function diffusion outside the dot, finite confinement barriers are considered. It is shown that the presence of the AlAs high potential barrier can account for the reported experimental blueshift when the AlAs layer is grown as a capping material, but this is not the case when the AlAs layer is grown in the substrate. An alternative explanation of the experimental data [Kim et al., J. Appl. Phys. 91, 5055 (2002)] based on our calculations is proposed. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]