The early stages of strained silicon relaxation during growth on (100) Si0.8Ge0.2 pseudo-substrates with a low threading dislocation density (3 x 104/cm2) were studied. Threading dislocations were observed in strained silicon layers only in the early stages of growth, whereas Shockley partial dislocations appeared at strained silicon thicknesses of above 18nm. By analyzing the dislocation types in various strained silicon layers, three different regimes of relaxation were observed for thicknesses below 15nm. No dislocation generation was observed for thicknesses between 15 and 18nm. The threading dislocation density increased, but no stacking faults were generated, for thicknesses above 18nm. The threading dislocation density decreased and the Shockley partial dislocation density increased due to the splitting of threading dislocations into partial dislocations. In this regime the stacking fault linear density exhibited a logarithmic dependence upon strained-silicon thickness. An analytical model was developed in order to describe the stacking fault linear density evolution with strained-silicon thickness and it was shown that the 18nm threshold thickness for dislocation splitting corresponded to an intrinsic stacking-fault energy of 90mJ/m2 in strained silicon.

Development of Analytical Model for Strained Silicon Relaxation on (100) Fully Relaxed Si0.8Ge0.2 Pseudo-Substrates. C.Figuet, O.Kononchuk: Thin Solid Films, 2010, 518[9], 2458-61