Complex optical signatures from quantum dot nanostructures and behavior in inverted pyramidal recesses

TL;DR

This paper investigates the complex optical and structural properties of InGaAs nanostructures grown on patterned GaAs substrates, revealing new nanostructure types and emphasizing the importance of growth parameters and design in quantum dot behavior.

Contribution

It uncovers a new type of InGaAs nanostructure—three corner quantum dots—and analyzes how growth conditions influence quantum dot properties and optical signatures.

Findings

Identification of three corner quantum dots in pyramidal structures

Growth temperature and barrier composition affect quantum dot emission energy

Complex dependence of optical properties on sample design

Abstract

A study of previously overlooked structural and optical properties of InGaAs heterostructures grown on (111)B oriented GaAs substrates patterned with inverted 7.5 um pitch pyramidal recesses is presented. First, the composition of the confinement barrier material (GaAs in this work) and its growth temperature are shown as some of the key parameters that determine the main quantum dot properties, including nontrivial emission energy dependence, excitonic pattern and unusual photoluminescence energetic ordering of the InGaAs ensemble nanostructures. Secondly, the formation of a formerly unidentified type of InGaAs nanostructures - three corner quantum dots - is demonstrated in our structures next to the well-known ones (a quantum dot and three lateral quantum wires and quantum wells). The findings show the complexity of the pyramidal quantum dot system which strongly depends on the sample design and which should be considered when selecting highly symmetric (central) quantum dots in newly designed experimental projects.