Intermixing of InAs/GaAs quantum dots by proton implantation and rapid thermal annealing

Low-temperature photoluminescence (PL) experiments have been carried out to investigate In/Ga intermixing in InAs/GaAs self-assembled quantum dots (QDs) by studying the changes in the optical properties of the system by rapid thermal annealing (RTA) and by room temperature proton implantation at various doses followed by RTA. The study of the RTA effect on the investigated structure shows that thermal stability can be ensured for an annealing temperature below 675 °C. For higher annealing temperatures, the thermal intermixing is found to change both the optical transition energy and the inter-sublevel spacing of the QD energy levels. By using proton implantation at various doses and subsequent annealing at 675 °C for 30 s, a tunable energy shift up to 130 meV has been obtained. The band gap tuning limit for this system has been achieved for an implantation dose of 5×1013 cm−2. Regardless of the intermixing technique employed, a pronounced PL peak broadening is found to occur at low annealing temperatures and/or proton implantation doses.