Estimating the Crystallographic Structure of AlGaN/GaN Heterostructure Buffer Layers Using Symmetric and Asymmetric X-ray Schemes

The possibility of using symmetric and asymmetric X-ray schemes on an XMD-300 single-crystal diffractometer to estimate the crystal structure of AlGaN/GaN heterostructure buffer layers is investigated. The developed algorithm for calculating the angles of incidence of a primary X-ray beam, angles of emergence of the diffracted beam to the AlN/GaN/Al 2 O 3 heterostructure surface, and diffraction angles for certain crystallographic planes of these materials allows us to obtain reflections from the and planes, which lie at angles to the surface. A study of the reflection shows that the crystal lattice of the transition layer between the Al 2 O 3 substrate and bulk GaN buffer layer is turned to the basal plane normal by an azimuthal angle of 30°. The embedding of С and Fe to the GaN buffer layer during a certain chosen growth process leads to a change in the GaN crystal structure, specifically, to the filling of vacant tetrapores through which the plane passes.