Composition determination of β-(AlxGa₁− x)₂O₃ layers coherently grown on (010) β-Ga₂O₃ substrates by high-resolution X-ray diffraction

We demonstrate X-ray-diffraction-based composition estimation of β-(Al x Ga 1− x ) 2 O 3 coherently grown on (010) β-Ga 2 O 3 . The relation between the strain along the [010] direction and the Al composition of the β-(Al x Ga 1− x ) 2 O 3 layer was formulated using the stress–strain relationship in the monoclinic system. This formulation allows us to estimate the Al composition using the out-of-plane lattice spacing determined by conventional X-ray ω–2θ measurements. This method was applied to molecular-beam-epitaxy-grown coherent β-(Al x Ga 1− x ) 2 O 3 /Ga 2 O 3 heterostructures, and the Al composition in β-(Al x Ga 1− x ) 2 O 3 agrees closely with the composition determined directly by atom probe tomography.