Multidirectional Observation of Photoluminescence Polarization Anisotropy in Closely Stacked InAs/GaAs Quantum Dots

Abstract

We studied polarization anisotropy observed in photoluminescence from closely stacked InAs/GaAs quantum dots (QDs). As the number of stacked layers was increased, the anisotropy in the (001) plane became drastically larger and the [001]-polarization component became larger than the [110] component when observed from the [ 110] direction. However, the polarization intensity of the [ 110] component remained stronger than that of the [001] component in the stacked QDs. Such varied polarization anisotropies depending on the observation direction have been found to result from the valence-band mixing in the vertically coupled electronic states. #

Effect of internal electric field on InAs/GaAs quantum dot solar cells

“…QDs were closely stacked along the growth direction so that the electronic states in the stacked QDs couple with each other. 20,21 Subsequently, p þ -GaAs/p-AlGaAs/p-GaAs/i-GaAs(2) layers were deposited on the stacked QD layers. The p layers were deposited at 500 C and the i-GaAs layer was at 480 C. The built-in electric field in the intrinsic layer was controlled by changing the thicknesses of the i-GaAs(1) and i-GaAs(2) layers.…”

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

“…The emission intensity ratio of the two states is determined by the degree of the valence band mixing. The cause of the valence band mixing can be complex, i.e., anisotropic strain distribution [22,23], nanostructure shape anisotropy (proven for strain-free QDs grown by droplet epitaxy method [24]), and increased nanostructure height resulting in decreased lh-hh energy separation [25,26]. In the first approximation two linearly polarized components are orthogonal and in the direction determined by the structure geometry.…”

Electronic and optical properties of [110]-tilted InAs/GaAs quantum dot stacks

“…The unique characteristics of the tilted QDSs are reported by highlighting highly asymmetrical biaxial strain distributions that regulate the electronic structure and polarization properties. It is predicted that by tilting the QDS, isotropic polarization response could be simultaneously realized from both [110] and [-110] cleaved- edge surfaces − a feature not accessible from the conventional [001]-aligned stacks [5][6][7] . The comparison of polar plots further revealed a high degree of control over the polarization properties attainable by tilting the QDSs, making it a useful tool for engineering the optical properties from the QD nano-structures.…”

“…5 4,7,16 are also shown by using diamond and triangle symbols. presence of hybridized H5 hole state around the center of the stack that contributes a drastic increase in the TM [001] mode.…”

“…This is a promising result because it shows that DOP [110] and DOP [−110] can be simultaneously reduced below zero, leading to an isotropic polarization response from both [110] and [-110] cleaved-edge surfaces. This kind of polarization response is not accessible from the conventional [001]-aligned QDSs that only provide isotropic emission either from the [110] cleaved-edge 4,5,7 or from the [-110] cleaved-edge 6 . The measured PL intensity polar plots showed a considerable difference between the angle of their peaks and the angle of tilt of the QDS obtained from TEM images 16 .…”