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 beta-(AlxGa1-x)(2)O-3 coherently grown on (010) beta-Ga2O3. The relation between the strain along the [010] direction and the Al composition of the beta-(AlxGa1-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 omega-2 theta. measurements. This method was applied to molecular-beam-epitaxy-grown coherent beta-(AlxGa1-x)(2)O-3/Ga2O3 heterostructures, and the Al composition in beta-(AlxGa1-x)(2)O-3 agrees closely with the composition determined directly by atom probe tomography. (C) 2016 The Japan Society of Applied Physics