Polarization anisotropy in the optical properties of silicon ellipsoids

TL;DR

This paper introduces a quantum mechanical approach to study the optical anisotropy in silicon ellipsoids, highlighting the significant role of surface polarization effects on their optical properties.

Contribution

The study demonstrates the importance of surface polarization in silicon ellipsoids and compares quantum mechanical results with classical models, revealing limitations of classical approaches for thin structures.

Findings

Surface polarization causes strong optical anisotropy in silicon ellipsoids.

Quantum and classical models differ significantly for thin, elongated structures.

Perpendicular and parallel dielectric responses depend differently on aspect ratio.

Abstract

A new real space quantum mechanical approach with local field effects included is applied to the calculation of the optical properties of silicon nanocrystals. Silicon ellipsoids are studied and the role of surface polarization is discussed in details. In particular, surface polarization is shown to be responsible for a strong optical anisotropy in silicon ellipsoids, much more pronounced with respect to the case in which only quantum confinement effects are considered. The static dielectric constant and the absorption spectra are calculated, showing that the perpendicular and parallel components have a very different dependence on the ellipsoid aspect ratio. Then, a comparison with the classical dielectric model is performed, showing that the model only works for large and regular structures, but it fails for thin elongated ellipsoids.