Characterization of GaAs substrates and epitaxial GaAs1−xPx layers by divergent x-ray beam diffraction
The application of the divergent x-ray beam diffraction method was studied for characterizing lattice imperfections, lattice parameters and composition variations and lattice strain in GaAs substrates and in GaAs1−xPx epitaxial layers. Reflection conics from {117}, {026}, {155} and (004) planes predominate in pseudo-Kossel back reflection patterns obtained from samples with (001) orientations. The sensitivity of pseudo-Kossel line displacements is assessed for lattice parameter and anisotropic strain distortion measurements. The lattice parameter of GaAs was determined to be 5.6435 ∢. Moseic subgrain misorientations in GaAs1−xPx epitaxial layers were found to be relatively independent of graded layer composition gradients, whereas homogeneous stress distortion was more strongly dependent.