High-resolution X-ray diffraction in coplanar and noncoplanar geometries has been used to investigate the influence of an SiN x nano-mask in the reduction of the threading dislocation (TD) density of high-quality AlGaN epitaxial layers grown on sapphire substrates. Our developed model, based on a Monte Carlo method, was applied to the simulation of the reciprocal-space maps of a two-layer system. Good agreement was found between the simulation and the experimental data, leading to an accurate determination of the dislocation densities as a function of the overgrowth layer thickness. The efficiency of the SiN x nano-mask was defined as the ratio of the TD densities in the AlGaN layers below and above the mask. A significant improvement in the AlGaN layer quality was achieved by increasing the overgrowth layer thickness, and a TD density reduction scaling law was established.
- epitaxial layers
- high-resolution X-ray diffraction
- threading dislocation density
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)