Effect of noncoherent islands on the optical properties of the 1.3 μm InAs/GaAs quantum dots during rapid thermal annealing

The effect of thermal annealing of InAs/GaAs quantum dots (QDs) with emission wavelength at 1.3 μm have been investigated by photoluminescence (PL) and transmission electron microscopy (TEM) measurements. There is a dramatic change in the PL spectra when the annealing temperature is raised up to 800°C: an accelerated blueshift of the main emission peak of QDs together with an inhomogeneous broadening of the linewidth. The TEM images shows that the lateral size of normal QDs decreases as the annealing temperature is increased, while the noncoherent islands increase their size and density. A small fraction of the relative large QDs contain dislocations when the annealing temperature increases up to 800 V. The latter leads to the strong decrease of the PL intensity.