Heteroepitaxial growth of MgO thin films on Al₂O ₃(0001) by metalorganic chemical vapor deposition

MgO thin films were epitaxially grown on Al₂O₃(0001) substrates using metalorganic chemical vapor deposition. For film growth, bis-cyclopentadienyl-Mg and oxygen were employed as reactants. X-ray diffraction (XRD) θ-2θ scan and θ-rocking curve data showed a preferred film orientation of [111] direction along Al₂O₃[0001]. The XRD rocking curve of films grown at 600°C showed a full width at half maximum as narrow as 0.45°, indicating good crystallinity. The pole figures of MgO thin films, which show clearly six poles with 60° of rotational symmetry, imply that the MgO films were epitaxially grown with either 60° twins or inversion domains. Based on the pole figure and azimuthal scan measurements, the epitaxial relationship of MgO(111)//Al₂O ₃(0001) and MgO[110]//Al₂O₃[1010] was determined. More importantly, the vertical alignment and surface morphology of the thin films were significantly improved by doping Zn during MgO film growth.