Optical response of layers of embedded semiconductor quantum dots

Abstract

The influence of the surrounding semiconducting matrix upon the polarizability of embedded nanoobjects (quantum dots) has been investigated. The previously proposed hybrid model has been extended to accommodate the influence of embedding. It turns out that excess discrete dipoles having an excess polarizability against a uniform background identical to the dielectric host material build the basis for a modified discrete dipole model, suited to describe the optical response of this system. The individual dipoles are described by means of dielectric embedded oblate ellipsoids as to their static response. An efficient description of the electrostatics of these ellipsoids has been given in terms of explicit functions using cylindrical coordinates and compatible with similar derivations for spherical dielectric objects. The dynamic contribution, responsible for frequency dependence is determined quantum mechanically and added to the embedded bare polarizability. The result of the model for the particular InAs quantum dot GaAs host combination investigated is a slightly decreased internal reflectance as compared to vacuum and an overall strong increment of the absorbance, the structure in the reflectance and of the ellipsometric angles.