Observations of new misfit dislocation configurations and slip systems at ultrahigh stresses in the (Al)GaAs/InxGa1−xAs/GaAs(100) system

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Abstract
We have observed new misfit dislocation configurations and slip systems in (Al)GaAs/InxGa1−xAs/GaAs(100) heterostructures for x≥0.4. Dislocations are observed running along 〈001〉 directions in the interface, which are inconsistent with conventional glide of misfit dislocations on {111} planes in the zincblende lattice. Diffraction contrast analysis in a transmission electron microscope (TEM) shows that these dislocations are of the edge type with b=a/2〈011〉, inclined at 45° to the interface. In situ TEM heating experiments reveal dislocation propagation velocities ∼tens of μm s−1 at 600 °C, suggesting that they are moving by glide, rather than climb. The only slip planes consistent with these observations are {101} planes inclined to the interface. This represents a new relaxation mechanism in highly strained semiconductor heterostructures.