Tuning of the Electronic Properties of Self-assembled InAs/InP(001) Quantum Dots by Rapid Thermal Annealing and Low-energy Ion Implantation

We have investigated the effect of post-growth rapid thermal annealing (RTA), grown-in defects technique and ion implantation on the low temperature photoluminescence (PL) spectra of self-assembled InAs/InP(001) quantum dots (QD). A blueshift up to 90 meV of the PL spectra is observed after RTA at 800 oC for 210s while no change in emission broadening is apparent. This behavior is consistent with inhomogeneous broadening dominated by monolayer height fluctuations in the population of QDs. The PL shifts are compared to those from calculation based on Fick diffusion model into thin quantum well (QW). In order to obtain larger blueshifts of the QD spectra, we have studied the effect of introducing point defects into thick InP layer, either by growing InP at low temperature or by implanting P atoms for different doses. PL shifts up to 250 meV are measured following RTA at 765 oC for 90 s using the grown-in defects technique. In the case of ion implantation, considerable shifts of the QD emission are obtained after RTA at 400 oC for 60s. For temperature of annealing above 500 oC, the PL spectra reveal an emission suggesting that the islands have essentially dissolved to form a diffused QW.