Epitaxial growth of NiO layers on MgO(001) and MgO(110)

About 33 nm thick NiO layers have been epitaxially grown on MgO substrate a t 900 degreesC. Investigations by X-ray diffraction, atomic force microscop y (AFM) and high resolution transmission electron microscopy (HRTEM) give e vidence for a close relationship between surface morphology and substrate o rientation. Deposited on MgO(0 0 1) surface, the NiO layer grows layer by l ayer leading to a flat NiO(0 0 1) surface. On the contrary, the surface of the NiO layers grown on MgO(l 1 0) has a roof-like morphology consisting of (I 0 0) and (0 1 0) facets elongated along the [0 0 1] direction. This par ticular surface configuration comes from a mechanism of surface energy rela xation during the growth process. (C) 2001 Elsevier Science B.V. ALI rights reserved.