Influence of matrix defects on the photoluminescence of InAs self-assembled quantum dots

We report the effect of defects that appear during capping layer growth or are introduced intentionally, on the photoluminescence (PL) properties of InAs strained quantum dots. A treatment of the samples with CCl4 during the growth leads to the reduction of native defect concentration in the GaAs matrix. This is shown to improve the emission intensity and to remove the quenching effect at room temperature. Some samples were subjected to proton irradiation in order to generate more defects in the matrix. The comparison between the emission from as-grown samples and irradiated ones shows a decrease of the PL intensity with the irradiation dose. However, no change in the activation energy for carrier's thermal escape was observed. The deterioration of the emission properties with the increasing irradiation dose is probably related to traps generated by the irradiation in the matrix, which reduce the overall concentration of the photocarriers.