Influence of pulsed laser annealing on the properties of Ge quantum dots in Si matrix

The laser annealing of Ge/Si heterostructures with Ge quantum dots (QD's) embedded on the depth of 0.15 and 0.3 μm has been studied. The samples were irradiated by 80-nanosecond ruby laser pulses. Irradiation energy density was close to the melting threshold of Si surface. The nanocluster structure was analyzed by Raman spectroscopy. Changes in composition of QD's were observed for both types of samples. The decrease in dispersion of nanocluster sizes after laser irradiation was obtained for samples with QD's embedded on 0.3 μm depth. The numerical simulations on the basis of Stefan problem showed that the maximum temperatures on the depth of QD's bedding differ by ~ 100 K. This difference is likely to lead to different effects of laser annealing of heterostructures with QD's.