XRD characterization of ZnO layers grown on GaAs(111)B, c-plane and a-plane sapphire substrates by plasma-assisted MBE

Structural evaluation of the ZnO epitaxial layers grown by plasma-assisted molecular beam epitaxy (PAMBE) on the GaAs (111)B, c -plane (0001) and a -plane (11-20) sapphire (α -Al2O3) substrates was demonstrated by using high-resolution X-ray diffraction (XRD). The in-plane epitaxial relationships between the ZnO layers and the substrates were found to be ZnO(0001) II GaAs(111) , ZnO(0001) IIα -Al2O3(0001) and ZnO (0001) II α -Al2O3(11-20) . All the ZnO layers were highly oriented to the c-axis but larger fluctuations of the c-axis were observed for the layers on the GaAs(111)B substrates. The lattice parameters of the ZnO layers were evaluated from the θ -2θ and ω -2θ scans, and reciprocal lattice mappings (RLMs). The in-plane compressive strains up to 0.3% in the ZnO layers on both the c -plane and a -plane sapphire substrates, and the in-plane tensile strains up to 0.4% in the ZnO films on the GaAs(111)B substrates were observed. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)