Heteroepitaxial growth of multidomain Ga2O3/sapphire(001) thin films deposited using radio frequency magnetron sputtering

We investigated heteroepitaxial growth of multidomain Ga2O3 thin films deposited using radio frequency magnetron sputtering onto sapphire(001) substrates. The crystalline orientation of the films was examined using high-resolution synchrotron X-ray diffraction. Corundum α- and monoclinic β-Ga2O3 coexisted in the as-grown samples. Azimuthal angle scans of the in-plane β(020) and α(303̄0) Bragg peaks revealed that the α-Ga2O3 and β-Ga2O3 both showed 12-fold in-plane rotational symmetry and, in particular, that the α-Ga2O3 domains rotated 30° to the in-plane direction were tilted ±3° to the sapphire[112̄0] direction. The optical bandgaps of the as-grown and annealed samples were estimated using ultraviolet-visible-infrared spectroscopy.