Evolution of InAs Quantum Dots during Annealing Process

InAs quantum dots were grown by molecular beam epitaxy in the Stranski-Krastanow growth mode and annealed under $N_2$ atmospheres at different temperatures. The evolution of quantum dots with the annealing temperature increasing were slightly different with the results reported in the literature. Atomic force microscopy investigations of quantum dots uncapped layer show a size initial increase followed by a prompt decrease as annealing temperature increases. It was found that the photoluminescence signal on quantum dots capped with GaAs layer was first slightly red-shifted and then blue-shifted with an increase in annealing temperature. The blue-shift can be attributed to In/Ga interdiffusion in annealing process. Red-shift of optical features indicates the change of the quantum dots compostion, size, and strain from the barrier.