Surface passivation and oxide encapsulation to improve optical properties of a single GaAs quantum dot close to the surface

TL;DR

This paper demonstrates that sulphur passivation combined with dielectric encapsulation improves the optical quality of GaAs quantum dots near the surface, making them more suitable for nanophotonic applications.

Contribution

It introduces a surface passivation and oxide encapsulation method that enhances emission linewidths and photoluminescence in shallow GaAs quantum dots.

Findings

Partial recovery of emission linewidths to bulk values

Increase in photoluminescence intensity

Effective surface passivation at 40 nm distance

Abstract

Epitaxial GaAs quantum dots grown by droplet etching have recently shown excellent properties as sources of single photons as well as entangled photon pairs. Integration in some nanophotonic structures requires surface-to-dot distances of less than 100 nm. This demands a surface passivation scheme, which could be useful to lower the density of surface states. To address this issue, sulphur passivation with dielectric overlayer as an encapsulation is used for surface to QD distances of 40 nm, which results in the partial recovery of emission linewidths to bulk values as well as in the increase of the photoluminescence intensity.