Polarization of emission from self‐assembled quantum dots and its application to the optical characterization of structure

Abstract

We revisit the optical anisotropy in quantum dots by using a tight‐binding approach. The mechanisms how shape anisotropy and strain field lead to optical anisotropy are identified. As the anisotropic structure of quantum dots imposes stronger confinement for the localized p‐orbitals aligning along the short axis, the valence‐band electrons prefer to occupy the orbitals aligning along the long axis, which leads to partially linear‐polarized interband emission. For intersubband transitions, the symmetry of those minor components from the valence bands in the electronic states is shown to account for the linear‐polarized absorption, which presents a picture different from that by the single‐band effective‐mass approximation. The dependence of polarization of the primary interband transition on the lateral aspect ratio of the structures is found to be insensitive to the random intermixing effects, which make it an appropriate tool for structure characterization. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The polarization response in InAs quantum dots: theoretical correlation between composition and electronic properties

“…We start our analysis by first assuming a uniform material profile throughout the QD geometry as in previous theoretical studies of the polarization response [4,5,10,23,31,32]. Quantum dots are assumed to be lens-shaped with the base diameter and height set at 15 nm and 5 nm, respectively, in accordance with the experimental TEM analysis [33].…”

“…Figure 1(b) plots the experimental normalized PL spectra taken under the two polarization conditions (TE and TM) and compares them with the theoretically calculated spectra for both the ideal case of a pure InAs QD and an In 0.7 Ga 0.3 As random alloy QD. The InGaAs alloy configuration has been suggested by some previous theoretical studies [23,31,32] to mimic the In-Ga intermixing effect.…”

Symmetry properties of n-doped (Cd,Mn)Te quantum well photoluminescence spectra: An exemplary evidence for anisotropy-induced valence-band mixing

“…This splitting, as well as specific features of the relevant optical transitions involving the split levels, originates from the anisotropic mixing perturbation in the lateral plane. The role and the nature of such perturbation has been analyzed in detail at a phenomenological and at a microscopic level, 9,13,18,19,20 and also experimentally. For example, the authors of Ref.…”