α-Al2O3/Ga2O3 superlattices coherently grown on r-plane sapphire

Ten-period binary α-Al2O3/Ga2O3 superlattices were fabricated on r-plane sapphire substrates by molecular beam epitaxy. By systematic variation of α-Ga2O3 thickness and evaluation through X-ray reflectivity and diffraction measurements and scanning transmission electron microscopy, we verified that the superlattice with α-Ga2O3 thickness up to ∼1 nm had coherent interfaces without misfit dislocation in spite of the large lattice mismatches. This successful fabrication of coherent α-Al2O3/Ga2O3 superlattices will encourage further development of α-(AlxGa1−x)2O3-based heterostructures including superlattices.