DETERMINING THE LATTICE-RELAXATION IN SEMICONDUCTOR LAYER SYSTEMS BY X-RAY-DIFFRACTION

This paper illustrates the procedure for extracting structural information available from x-ray diffraction space mapping and topography. The methods of measuring, the residual strain, macroscopic tilts, microscopic tilts and their lateral dimensions, and the strain field disruption emanating from the interfacial defects are presented. Partially relaxed thick InGaAs layers on GaAs substrates were studied and it was concluded that the relaxation and macroscopic tilting were anisotropic, the microscopic tilting reduced with thickness, and the interfacial disruption did not continue to increase with increasing relaxation. A ''mosaic grain growth'' model is postulated to account for the diminishing microscopic tilt spread and increasing topographic contrast with layer thickness.