Impurity Doping Effect on the Dislocation Density in GaAs on Si (100) Grown by Migration-Enhanced Epitaxy

Dislocation density in GaAs epilayers grown on Si substrates by migration-enhanced epitaxy can be reduced by heavy doping of Si without using strained-layer superlattices or repeated annealing procedures. This effect is demonstrated by TEM and EBIC observations. The EBIC topographic observations show that the dislocation density of 6-µm-thick nonoptimized samples is approximately 4×10 6 cm -2 , which compares favorably with the value of ∼1×10 7 cm -2 in undoped samples. The bent dislocations are mostly arranged parallel to the steps which exist on a tilted substrate surface.