Interface structure and anisotropic strain relaxation of nonpolar wurtzite (112¯) and (101¯) orientations: ZnO epilayers grown on sapphire

• DOI: 10.1063/1.2996248
• Publication Date: 2008-10-15T14:06:26Z
• Authors: J.-M. Chauveau; P. Vennéguès; M. Laügt; C. Deparis; J. Zuniga-Perez; C. Morhain
• Keywords: Wurtzite crystal structure; Stress relaxation; Lattice (music)

The interface properties between nonpolar ZnO and sapphire have been studied using high resolution transmission electron microscopy. Two orientations are investigated: a- m-orientations corresponding to [112¯0] [101¯0] crystallographic directions. After the definition of epitaxial relationships resulting initial lattice mismatch, we show that can be grown on with perfectly flat interfaces. Geometrical misfit dislocations observed at ZnO/sapphire their density gives residual strain in layer. A strong anisotropy relaxation is found along two perpendicular in-plane This may explained terms anisotropic mismatch yielding different processes. domain matching epitaxy m- a-oriented layers for mismatches larger than 9% while a epitaxy, which driven by nucleation glide dislocations, [0001] direction. In order explain activated slip systems calculated both as function stress due mismatch. There major difference from polar orientations. Low energy prismatic effective plastic because they no longer parallel growth direction, case c-oriented layers, nor applied stress. Our results directly extended other wurtzite structures such III-nitrides.