X-ray diffraction of relaxed InGaAs heterostructures grown on misoriented (100) GaAs substrates

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Abstract
The authors report the study of X-ray diffraction profiles from an InGaAs/GaAs heterostructure grown on a (100) substrate misoriented with an offcut angle of about 2 degrees toward the (110) direction. The angular positions of the substrate and epitaxial layer peaks, the peak spacing and the intensity ratio are seen to vary with the azimuthal angle phi . These measurements provide an accurate value of the substrate misorientation epsilon and of the tilt angle alpha between the (100) planes of the substrate and the epitaxial layer. The value of this tilt angle is compared with other results on similar lattice mismatched structures. The authors' data show that strain relaxation in thick lattice mismatched epitaxial layers grown on misoriented substrates is partly achieved via a reorientation of the lattice planes.