The quantum dot composition, growth methods, and implant conditions were expected to play a major role in the interdiffusion of the quantum dots. Interdiffusion processes in In0.5Ga0.5As quantum dots, caused by ion implantation and subsequent annealing, were studied. The H, He and Kr ions were implanted at various doses (1011–5 x 1015/cm2) and implant temperatures (ambient to 300C). Low-temperature photoluminescence measurements were used to investigate the influence of various implantation parameters on the interdiffusion process. It was found that the photoluminescence energy shifts increased with the concentration of residual defects in the samples. Implantation at elevated temperatures reduced the amount of photoluminescence energy shift, but an enhanced recovery of the luminescence was observed. Much less interdiffusion took place for the high-temperature implants, due to significant dynamic annealing. At above 150C, hardly any change was seen in the energy shifts for light ion species. Elevated temperatures do not show any effect on the variation of energy shift for the Kr implanted quantum dots. This was due to the formation of denser collision cascades during Kr implantation, which generated thermally stable defects. It was shown that the degree of energy shift was related to the choice of the correct implantation conditions, which was crucial in order to achieve an optimized and effective interdiffusion process.

Implantation Induced Interdiffusion of InGaAs Quantum Dots - Effect of Ion Species, Dose and Substrate Temperature. S.Ahmed, K.Amirov, U.Larsson, J.Lin, A.Haq, P.Too, Z.Tabatabaian: Vacuum, 2005, 78[2-4], 137-41