Implantation induced interdiffusion of InGaAs quantum dots-effect of ion species, dose and substrate temperature

The quantum dot (QD) composition, growth methods, and implant conditions are expected to play a major role in the interdiffusion of the QDs. In this work, interdiffusion process in In0.5Ga0.5As QDs caused by ion implantation and subsequent annealing is studied. Hydrogen, helium and krypton ions are implanted at various doses (1×1011-5×1015 cm−2) and implant temperatures (RT-300 °C). Low temperature photoluminescence (PL) measurements are made to investigate the influence of various implantation parameters on the interdiffusion process. It is found that the PL energy shifts increase with the concentration of residual defects in the samples. Implantation at elevated temperatures reduces the amount of PL energy shift, but enhanced recovery of the luminescence is observed. Much less interdiffusion takes place at the elevated temperature implants due to significant dynamic annealing. For the temperatures above 150 °C, hardly any change is seen in the energy shifts for light ion species. Elevated temperatures do not show any effect on the variation of energy shift for the krypton implanted QDs. This is due to the formation of denser collision cascades during krypton implantation, which generates thermally stable defects. It is shown that the degree of energy shift is related to the choice of the right implantation conditions, which is crucial to achieve an optimised and effective interdiffusion process.