Low etch pit density GaAs on Si grown by metalorganic chemical vapor deposition

GaAs was grown on a Si substrate by metalorganic chemical vapor deposition using GaAs/GaAsP strained-layer superlattice (SLS) intermediate layers. The dislocation density decreases at the interface between GaAs and the SLS, but does not decrease in the SLS. When a GaAs/GaAsP SLS is used as the intermediate layer, part of the threading dislocation propagates into the top GaAs layer because of the lattice mismatch of GaAs and SLS. The low etch pit density of (3–5)×105 cm−2 was obtained by using the intermediate layer of a GaAs/GaAsP SLS and an AlAs/GaAs superlattice with thermal cycle annealing.