Strain and misorientation in GaAs grown on Si(001) by organometallic epitaxy

Abstract

Epitaxial GaAs grown on Si(001) by organometallic vapor phase epitaxy has been characterized for strain and misorientation, using double-crystal x-ray diffraction. (004) and (115) rocking curves indicate that the GaAs is under biaxial tensile stress, σ∥≊2.1×109 dyn/cm2, and is tetragonally distorted with unit cell dimensions 5.6424±0.0012 Å and 5.6656±0.0012 Å. The dislocation density in the GaAs, determined from the rocking curve width, is less than 4.2×107 cm−2. The GaAs(001) axis is tilted with respect to the Si(001), toward the substrate normal. This misorientation is a strain relief mechanism and is caused by shear strain energy in the nucleating GaAs.