Engineering the hole confinement for CdTe-based quantum dot molecules

TL;DR

This paper presents a method to control quantum confinement in CdTe quantum dot molecules by using different lattice materials for barriers, enabling the tuning of hole states and the formation of molecular states.

Contribution

The study introduces a novel approach to engineer hole confinement in quantum dot molecules through lattice mismatch, verified by microscopy and photoluminescence.

Findings

Successful tuning of hole energy levels with electric field

Observation of molecular state formation at resonance

Correlation between morphology and optical properties

Abstract

We demonstrate an efficient method to engineer the quantum confinement in a system of two quantum dots grown in a vertical stack. We achieve this by using materials with a different lattice constant for the growth of the outer and inner barriers. We monitor the resulting dot morphology with transmission electron microscopy studies and correlate the results with ensemble quantum dot photoluminescence. Furthermore, we embed the double quantum dots into diode structures and study photoluminescence as a function of bias voltage. We show that in properly engineered structures, it is possible to achieve a resonance of the hole states by tuning the energy levels with electric field. At the resonance, we observe signatures of a formation of a molecular state, hybridized over the two dots.