Controlled Formation of Misfit Dislocations for Heteroepitaxial Growth of GaAs on (100) Si by Migration-Enhanced Epitaxy

The strain relaxation by formation of misfit dislocations for GaAs epitaxial layers on (100) Si is investigated by wafer bending measurements and transmission electron microscopy (TEM) studies. The formation of misfit dislocations depends not only on the growth temperature but also on the substrate offorientation. The effective suppression of the dislocation formation at low temperatures leads to a more controlled generation than that under equilibrium conditions. This mechanism is demonstrated by realizing nonbending GaAs/Si wafers. Under appropriate growth conditions, a regular dislocation array at the interface is created, leading to a drastic reduction of dislocations in the GaAs epitaxial layer.