α-Al2O3/Ga2O3superlattices coherently grown onr-plane sapphire

Ten-period binary α-Al 2 O 3 /Ga 2 O 3 superlattices were fabricated on r -plane sapphire substrates by molecular beam epitaxy. By systematic variation of α-Ga 2 O 3 thickness and evaluation through X-ray reflectivity and diffraction measurements and scanning transmission electron microscopy, we verified that the superlattice with α-Ga 2 O 3 thickness up to ∼1 nm had coherent interfaces without misfit dislocation in spite of the large lattice mismatches. This successful fabrication of coherent α-Al 2 O 3 /Ga 2 O 3 superlattices will encourage further development of α-(Al x Ga 1− x ) 2 O 3 -based heterostructures including superlattices.