The dissociation of dislocations in undeformed SixGe1-x crystals, with low (x = 0.05) and high (x = 0.5) Si contents, grown from the melt was investigated using the weak-beam electron microscopy technique. Dislocations with total Burgers vectors of b = ½<110> and of various orientations were found to be dissociated into Shockley partials; separated by an intrinsic stacking fault on a {111} glide plane. Extended dislocation nodes were also observed. For x = 0.05, the dissociation widths of single dislocations ranged from Δ = 3.5nm for screw orientations to Δ = 6.2nm for edge orientations. The corresponding values for x = 0.5 were higher, with separations of between Δ = 3.9nm and Δ = 6.9nm. Stacking-fault energies of 56mJ/m2 for x = 0.05 and of 53mJ/m2 for x = 0.5 were deduced from measurements of the dissociation widths as a function of dislocation orientation, using anisotropic elasticity theory.

Dislocations and their Dissociation in SixGe1- x Alloys. D.Stenkamp, W.Jäger: Philosophical Magazine A, 1992, 65[6], 1369-82

Table 6

Dislocation Dissociation Widths and

Stacking-Fault Energies for Ge1-xSix Alloys