Centrosymmetric PbTe/CdTe quantum dots coherently embedded by epitaxial precipitation

TL;DR

This paper demonstrates a novel method to create highly symmetric, strain-free PbTe/CdTe quantum dots embedded in a crystalline matrix via epitaxial precipitation, with potential for mid-infrared photonic applications.

Contribution

It introduces a new epitaxial precipitation technique to fabricate symmetric, strain-free quantum dots in a heterosystem with near thermodynamic equilibrium.

Findings

Quantum dots are approximately 25 nm in size.

Quantum dots exhibit intense room temperature luminescence at 3.2 micrometers.

The method produces quantum dots with near strain-free, symmetric shapes.

Abstract

A concept for the fabrication of highly symmetric quantum dots that are coherently embedded in a single crystalline matrix is demonstrated. In this approach, the formation of the quantum dots is induced by a transformation of an epitaxial 2D quantum well into an array of isolated precipitates with dimensions of about 25 nm. The formation process is driven by the immiscibility of the constituent materials resulting from their different lattice structures. The investigated PbTe/CdTe heterosystem combines two different cubic lattices with almost identical lattice constants. Therefore, the precipitated quantum dots are almost strain free and near thermodynamic equilibrium they exhibit the shape of small-rhombo-cubo-octahedrons. The PbTe/CdTe quantum dots, grown on GaAs substrates, display intense room temperature luminescence at wavelength around 3.2 micrometer, which makes them auspicious for applications in mid-infrared photonic devices.