Study of ZnO nanostructures grown by a hydrothermal process on GaP/ZnO nanowires

ZnO is a prominent material for creation of nanostructures as a multifunctional material for broad applications in blue and ultraviolet optoelectronics. A lot of efforts have been dedicated to understand the unique properties of nanostructured materials. The main purpose of this work is to verify (1) the technology of thin ZnO films deposition by RF magnetron sputtering to cover round GaP nanowires prepared by metalorganic vapor phase epitaxy, and (2) the hydrothermal growth of core/shell ZnO nanostructures on both GaP/ZnO and GaP/ZnO structures and nanowires deposited by RF magnetron sputtering. SEM, XRD, optical ellipsometry and micro-Raman measurements were employed to investigate the structural and optical properties of GaP/ZnO structures as well as core/shell nanostructures. The thickness, columnar structure and surface layer roughness of the deposited ZnO layers were estimated from cut-edge SEM images and verified by spectral ellipsometry. The measured XRD intensity patterns of (0 0 2) ZnO line of hydrothermally grown ZnO nanoclusters on nanowires show a narrow spectral width ∼0.17° which indicates a good crystalline structure in comparison with ZnO films prepared by magnetron sputtering on GaP substrate, even after their annealing. The PL spectra of the hydrothermally grown GaP/ZnO core/shell nanostructure show typical near band emission and very strong yellow broadband emission from Zn(OH)2 or hydroxyl groups for ZnO structures. For the first time we have demonstrated formation of GaP/ZnO core/shell nanostructured arrays on GaP nanowires grown by hydrothermal process.