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Local Droplet Etching Yields More Symmetric Quantum Dots for Integrated Photonics

Researchers at Johannes Kepler University and the State University of Campinas have demonstrated a local droplet etching (LDE) technique to fabricate InGaAs quantum dots embedded in AlGaAs with unprecedented symmetry and low surface density. The dots exhibit radiative lifetimes around 300 ps—about three times faster than conventional Stranski‑Krastanov (SK) grown dots—and their emission can be tuned from 780 nm to 900 nm. By filling nanocavities with a thin InGaAs layer, the method yields fine‑structure splitting comparable to the best GaAs droplet‑etched dots, supporting entangled‑photon generation. The larger s‑p electronic level spacing suggests potential operation at temperatures exceeding 40 K, advancing integrated quantum photonic devices.