Strain nonuniformity in GaAs heteroepitaxial films on Si(001) studied by x-ray diffraction

Abstract

High-resolution x-ray diffraction measurements are used to fully characterize the strain state of relaxed highly mismatched GaAs films, grown on vicinal Si (001) substrates by molecular beam epitaxy. The nonuniformity of the misfit dislocation network at the GaAs∕Si (001) interface is studied by analyzing the profiles of x-ray diffraction peaks and the reciprocal space maps for different reflections. The detailed analysis of the peak positions shows a dependence of the relaxation on the crystallographic direction, with the relaxation being larger in the direction perpendicular to the α-dislocation lines. Based on analytical expressions for the full width at half maximum in the longitudinal and transverse sections, an advanced version of the Williamson-Hall plot [Acta Metall. 1, 22 (1953)] is proposed that takes into account the geometry of dislocation distribution and the scattering geometry. We show that this type of analysis can reveal both the type and density of misfit dislocations. The measured peak widths are attributed to random uncorrelated 60°-type misfit dislocations with density much smaller than the total dislocation density required for lattice-mismatch relaxation. The major part of the GaAs∕Si lattice mismatch is accommodated by periodic arrays of edge-type perfect dislocations that do not cause nonuniform strain in the film. The applied theoretical and experimental analysis is easily applicable on other zinc blende highly lattice-mismatched systems.

Bunches of misfit dislocations on the onset of relaxation of Si0.4Ge0.6/Si(001) epitaxial films revealed by high-resolution x-ray diffraction

“…However, the dislocations are still much less ordered than typically observed in other systems, where the correlation parameter c occurs much smaller than 1. 16,[38][39][40] Less correlated dislocation distribution in the present case can also be a consequence of the low growth temperature.…”

Characterization of dislocations in germanium layers grown on (011)- and (111)-oriented silicon by coplanar and noncoplanar X-ray diffraction

“…To process the data we propose to use a simple and illustrative approach close to a modification of the Williamson-Hall plot, which is intensively used in microstructure analysis of powder and polycrystalline samples (Ungá r, 2001) [Shalimov et al (2007) take a similar approach for application to heteroepitaxial film analysis]. The basis of the approach is to analyze the peak width dependence on the reflection.…”

Interfacial Misfit Array Technique for GaSb Growth on GaAs (001) Substrate by Molecular Beam Epitaxy

“…26,28 For GaSb layers grown on the GaAs substrate, the K parameter is 11.805 for DQ x and 8.347 for DQ z . 29 Moreover, the correlation factor c is equal to 0.015 for DQ x and 0.005 for DQ z .…”