Strong configuration mixing due to dielectric confinement in semiconductor nanorods

The interaction between electron-electron and electron-hole pairs in semiconductor nanorods embedded in dielectric media is investigated using a configuration-interaction method. Contrary to spherical quantum dots of similar volume, the dielectric confinement is shown to bring nanorods into a regime of strong configuration mixing. The wave functions are particularly sensitive to such mixing, which leads to qualitative changes in the electronic and optical properties of the rods.

Figure 1

(Color online) Two-electron ground-state properties in a NR (solid line) and a spherical NC (dashed line) of the same volume, as a function of the dielectric constant of the surrounding medium. (a) Electron-electron repulsion energy. (b) Weight of configuration mixing in the CI expansion. The inset represents the energy coming from Coulomb correlation (see text).

Figure 2

(Color online) Two-electron ground-state charge density along the vertical axis of a NC (left) and a NR (right) with (solid line) and without (dotted line) dielectric confinement. The insets are schematics of the structures under study.

Figure 3

(Color online) Same as Fig. 1, but for the exciton ground state.

Figure 4

(Color online) (a) Recombination probability of the ground-state exciton as a function of the dielectric constant of the surrounding medium, in a NR (solid line) and a NC (dashed line) of the same volume. (b) Absorption spectrum of the NR under a weak electric field, in the absence and presence of dielectric confinement. The spectra are offset for clarity. The high-energy peak at ${\epsilon }^{\text{out}}=2.0$ arises from Coulomb correlations.