Heteroepitaxial Growth of MgO Thin Films on Al2O3(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)//Al2O3(0001) and MgO[10]//Al2O3[100] was determined. More importantly, the vertical alignment and surface morphology of the thin films were significantly improved by doping Zn during MgO film growth.