High-density GaAs/AlGaAs quantum dots formed on GaAs (3Â 1Â 1)A substrates by droplet epitaxy

We investigated the self-assembly of GaAs/AlGaAs quantum dots (QDs) on GaAs (3 1 1)A substrates by droplet epitaxy. High-density Ga droplets were formed on the (3 1 1)A surfaces due to the short surface migration distance of Ga atoms. The maximum area density exceeded 1011 /cm2. These Ga droplets were crystallized into dot-shaped nanostructures (QDs) even by the irradiation of low As4 flux intensity. The capped GaAs QDs exhibited efficient, narrow PL emission at 5 K, indicating their high quality and uniformity.