Fig. 1: Effusion cell geometry and QD density modulation.

a Schematic representation of the gradient of material coverage on the substrate in top view (left) and geometrical configuration of the gallium effusion cell inside the MBE growth chamber viewed from the side (right). b Ensemble photoluminescence (PL) spectrum at 100 K with a laser spot size of ~100 µm from a 210 s annealed sample (white star). The different peaks correspond to the different dipole and parity allowed interband transitions between orbital states. c False color PL maps recorded from 3″ wafers with a nominally 15 nm thick GaAs pattern defining layer (PDL). The QD PL intensity is spectrally integrated over the region between 1000 and 1300 nm. The wafers were annealed before the QD growth for 0 s, 210 s, and 600 s, respectively. d Michelson contrast at medium densities versus the annealing time. Error bars represent the standard deviation.