Growth of homoepitaxial ZnO film on ZnO nanorods and light emitting diode applications

Vertically aligned ZnO nanorod arrays with a diameter of 40-150 nm were fabricated on Al₂O₃ substrates with and without GaN interlayers, and consequently covered with a ZnO film in situ by a catalyst-free metal-organic vapour phase epitaxy method. X-ray diffraction and transmission electron microscopy measurements demonstrated that the ZnO film/nanorods hybrid structures had a well-ordered wurtzite structure with no lattice mismatch between the film and nanorods, and that the film was homoepitaxially grown horizontally as well as vertically on the pre-grown nanorods. From n-ZnO film/nanorods/p-GaN heterojunctions, we observed a blue light emission with a wavelength of about 440 nm.