Migration enhanced epitaxy growth of GaAs on Si with (GaAs)1−x (Si2)xGaAs strained layer superlattice buffer layers

Abstract

(GaAs)1−x(Si2)x/GaAs strained-layer superlattices (SLS) have been used as buffer layers to reduce the dislocation density in GaAs grown on Si by migration enhanced epitaxy (MEE). Double-crystal x-ray diffractograms of GaAs on Si grown using MEE with 3 packets of 5 period (GaAs)1−x(Si2)x/GaAs SLS buffer layers, exhibited a GaAs (004) peak full width at half maximum value of 150 arcsecs. The cross-sectional transmission electron microscopy investigations revealed extensive threading dislocation bending at each interface of (GaAs)1−x(Si2)x and GaAs, making the SLS highly efficient. The observed highly effective dislocation bending, we believe is due to a combined effect of built-in strain in the SLS and the relatively high elastic stiffness constant of (GaAs)1−x(Si2)x alloys. Plan-view transmission electron microscopy studies indicated dislocation densities <5×105 cm−2 at a distance of 0.2 μm from the surface of GaAs on Si.