Determination of lattice plane curvature and dislocation Burgers vector density in crystals by rocking curve imaging technique

摘要

In the present work the lattice plane curvature of a nearly dislocation free S:doped InP and a semiinsulating GaAs wafer crystals has been investigated using the method of X-ray rocking curve imaging based on the FRELON CCD area detector with a pixel resolution from 10 to 40 μm at the ID 19 ESRF beamline. The geometry of the experiment is based on a vertical Si (111) monochromator and a horizontal sample scattering planes in the Bragg geometry (σ-π geometry). To determine the local lattice inclination, the effect of such dispersive setup on the measured local diffraction peak position has been accurately determined and the equations to determine the lattice plane curvature of the crystals under the condition of isotropic distribution of dislocation Burgers vectors are obtained. The analysis of the data showed that the shift of the Bragg condition is almost completely due to the lattice tilt rather than to the lattice parameter variation. Lattice displacements from the ideal lattice as large as 200 μm are found at the edges of the InP crystal. Non random distributions of dislocation Burgers vectors are observed in both samples.