Micropillars with a controlled number of site-controlled quantum dots

TL;DR

This paper demonstrates the fabrication of micropillars with precisely positioned, high-quality site-controlled quantum dots using a buried stressor approach, achieving high Q-factors and Purcell enhancement for quantum photonic applications.

Contribution

It introduces a novel method for integrating a controllable number of site-controlled quantum dots into micropillars with high optical quality and positional accuracy.

Findings

Achieved Q-factors up to 12000 at 930 nm emission.

Demonstrated Purcell enhancement with F_P = 4.3 ± 0.3.

Controlled the number and position of quantum dots via design of the buried stressor.

Abstract

We report on the realization of micropillars with site-controlled quantum dots (SCQDs) in the active layer. The SCQDs are grown via the buried stressor approach which allows for the positioned growth and device integration of a controllable number of QDs with high optical quality. This concept is very powerful as the number and the position of SCQDs in the cavity can be simultaneously controlled by the design of the buried stressor. The fabricated micropillars exhibit a high degree of position control for the QDs above the buried stressor and $Q$-factors of up to 12000 at an emission wavelength around 930 nm. We experimentally analyze and numerically model the cavity $Q$-factor, the mode volume, the Purcell factor and the photon-extraction efficiency as a function of the aperture diameter of the buried stressor. Exploiting these SCQD micropillars, we experimentally observe the Purcell enhancement in the single-QD regime with $F_P$ = 4.3 $\pm$ 0.3.