A detailed study of the effects of rapid thermal annealing on the luminescence properties of InAs sub-monolayer quantum dots

We studied the effects of post-growth annealing on InAs sub-monolayer samples with different numbers of quantum dot stacks embedded in InGaAs wells. Four samples, with 4, 6, 8, and 10 dot stacks, were grown with solid phase, molecular beam epitaxy under invariant conditions. Increasing the number of stacks created a gradual shift in the photoluminescence ground-state transition energy of the samples from 1.195 to 1.111 eV. Subjecting the samples to post-growth thermal annealing at 650, 700, 750, and 800 °C produced a typical blue-shift. The full-width-half-maxima of the emission spectrum narrowed with an increase in annealing temperature. All samples exhibited significant enhancement in their activation energies when annealed at 650 °C, suggesting that annealing healed defects created during sample growth.