Deposition and Characterizations of ZnO Thin Films on Al2O3 (0001) Substrates with III-Arsenide Intermediating Layers

Abstract

ZnO thin films have been grown by radio-frequency magnetron sputtering on c-plane sapphire substrates with III-V (i.e., GaAs and InAs) intermediate layers. The intermediate layers were grown by molecular beam epitaxy. Structural and optical properties were studied by X-ray diffraction (XRD) and Raman scatterings. The growth orientations of the ZnO/III-V/c-sapphire heterostructures were determined by off-axis XRD, i.e., x-ray pole-figure mapping. It is found that the crystalline quality of the III-V intermediate layers play an important role in the growth of ZnO. The 30-degree in-plane rotation that usually occurs in the growth of ZnO on a c-sapphire substrate is absent due to the insertion of III-V intermediate layers. Raman scattering, together with the XRD, reveals the relaxation of the tensile strain in the GaAs interlayer after the ZnO thin film deposition, while the strain relaxation did not occur in the InAs interlayer. PACS: B1 ZnO, B2 semiconductors, A3 physical vapor deposition process.