Quadrangular ZnO:Cu nanocombs: mechanism and optical properties

Abstract

Cu-doped ZnO nanocombs were fabricated on Si substrate by a simple chemical vapor deposition method. Scanning electron microscopy analyses indicate that the single nanocomb tooth has a quadrangle structure. We propose that the synthesis of the Cu-doped ZnO nanocombs includes the formation of Cu/Zn core of square-like and surface oxidation. The structural and optical properties of the ZnO:Cu nanocombs were investigated by X-ray diffraction, photoluminescence, and Raman spectra. The results show that native point defects were introduced with increasing of the Cu composition by the substitution of Cu2+ at Zn2+ lattice sites. Meanwhile, the photoluminescence show that the visible luminescence greatly enhances by the introduction of Cu and the annealing in vacuum (1 × 10−4 Pa). Magnetization measurements show that Cu-doped ZnO nanocombs exhibit room-temperature ferromagnetism (RTFM), and the ferromagnetism increases with the Cu composition. It was suggested that the origin of the enhanced RTFM in ZnO:Cu nanocombs are related to the increased intrinsic lattice defects and vacancies oxygen.