Misfit dislocation interactions in low mismatch p/p<sup>+</sup> Si
P Feichtinger; B Poust; M S Goorsky; D Oster; J Chambers; J Moreland
Журнал:
Journal of Physics D: Applied Physics
Дата:
2001-05-21
Аннотация:
We studied the propagation and interaction of individual misfit dislocations in strained p/p<sup>+</sup> Si wafers. Relaxation of misfit strain occurs at the wafer edge during high-temperature epitaxial growth. The thick epitaxial layer (about five times the critical thickness) and low misfit dislocation densities (~100 cm<sup>-1</sup>) are highly compatible with a non-destructive study via x-ray topography. We determined that as a gliding 60° misfit dislocation encounters a strain field in its path, it cross-slips to a specific lattice direction. Misfit dislocation segments with either an orthogonal or quasi-parallel (in the case of the off-oriented substrate) glide direction of the Burger's vector were determined to act as cross-slip initiation sites. This interaction happens during layer growth as well as post-growth annealing cycles. We did not find a case of misfit dislocation blocking during sample annealing. No occurrence of annihilation or multiplication reaction of crossing dislocations was detected during our studies. We show that, due to geometry, a distribution of tilt across the wafer surface results from preferential cross-slipping events. Our results are applicable to early stages of strain relaxation in other strained systems, like graded buffer layers.
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