Ultranarrow Luminescence Lines from Single Quantum Dots

TLDR

Quantum dots were fabricated by molecular beam epitaxy using a strain‑induced self‑organizing mechanism. Ultranarrow (<0.15 meV) cathodoluminescence lines from single InAs quantum dots in GaAs were observed up to 50 K, confirming δ‑function‑like electronic states, with a narrow size distribution (12 ± 1 nm) and a dense array producing an absorption peak that aligns with the luminescence maximum.

Abstract

We report ultranarrow $(&lt;0.15\mathrm{meV})$ cathodoluminescence lines originating from single InAs quantum dots in a GaAs matrix for temperatures up to 50 K, directly proving their $\ensuremath{\delta}$-function-like density of electronic states. The quantum dots have been prepared by molecular beam epitaxy utilizing a strain-induced self-organizing mechanism. A narrow dot size distribution of width $12\ifmmode\pm\else\textpm\fi{}1\mathrm{nm}$ is imaged by plan-view transmission electron microscopy. Cathodoluminescence images directly visualize individual dot positions and recombination from a single dot. A dense dot array $(\ensuremath{\sim}{10}^{11}\mathrm{dots}/{\mathrm{cm}}^{2})$ gives rise to a distinct absorption peak which almost coincides with the luminescence maximum.