INTERDIFFUSION-ASSISTED DISLOCATION MIGRATION IN GAAS/GA1-XALXAS LAYERS ON SI(001)

Lateral dislocation migration has been observed at interfaces in epitaxial GaAs/Ga1-xAl(x)As layers grown on GaAs/Si(001) films. Observations are reported, suggesting that the passage of these dislocations results in layer interdiffusion in a band of material 25-50 angstrom thick parallel to the slip plane. A new mechanism is proposed whereby the lowering of total film energy by interdiffusion provides a driving force for dislocation migration. For GaAs/Ga1-xAl(x)As at the growth temperature of 600-degrees-C, the driving force can be up to 70 times greater than that possible by relief of misfit strain energy. It is estimated that interdiffusion-assisted dislocation migration may be important in systems where the natural mismatch is up to 2-3%.