SELF-ADJUSTMENT OF MISFIT DISLOCATIONS IN COMPOSITIONALLY GRADED SI1-XGEX LAYERS

A model is developed which predicts an ordering of the dislocation mul tiplication sources in Si1-xGex/Si heteroepitaxial systems. This order ing results in an increased probability for threading dislocations to annihilate. It is shown that, following certain selection rules for di slocation multiplication, an infinite three-dimensional network of mis fit dislocations can develop throughout the compositionally graded Si1 -xGex layer. The model is consistent with existing experimental data.