Growth of c-plane ZnO on γ-LiAlO2 (100) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy

C-plane ZnO epilayers were grown on LiAlO2 (100) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy. Both the X-ray rocking curves and the transmission electron microscopy analyses indicate that the ZnO epilayers exhibit a lower threading dislocation density (similar to 1 x 10(10) cm(-2)) as compared to those grown on LiAlO2 substrate without the buffer layer. A high Zn/O flux ratio is beneficial for reducing the density of screw-type dislocations. Reciprocal space maps demonstrate that the misfit strain has been relaxed. No interfacial layer is formed at the ZnO/GaN interface by using a Zn pre-exposure strategy. The ZnO epilayers exhibit a strong near band edge emission at 3.28 eV at room temperature with a negligible green band emission. (C) 2015 Elsevier B.V. All rights reserved.