Defect induced room temperature ferromagnetism in well-aligned ZnO nanorods grown on Si (100) substrate

In this work, we report the fabrication of high quality single-crystalline ZnO nanorod arrays which were grown on the silicon (Si) substrate using a microwave assisted solution method. The as grown nanorods were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photo-luminescence (PL) and magnetization measurements. The XRD results indicated that the ZnO nanorods are well oriented with the c-axis perpendicular to the substrate and have single phase nature with the wurtzite structure. FE-SEM results showed that the length and diameter of the well aligned rods is about ~ 1 μm and ~ 100 nm respectively, having aspect ratio of 20–30. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at ~ 583 nm might be attributed to surface oxygen vacancies or defects. Magnetization measurements show that the ZnO nanorods exhibit room temperature ferromagnetism which may result due to the presence of defects in the ZnO nanorods.