Fabrication of porous ZnO nanorods with nano-sized pores and their properties

Porous ZnO nanorods were fabricated by using an annealing process at 300, 500, and 700 °C for 20 min in an argon atmosphere. The structural and the optical properties of the porous ZnO nanorods were characterized by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and photoluminescence (PL). The pore density of the porous ZnO nanorods decreased and the average diameter of the pores increased with increasing annealing temperature. The intensity of the ZnO (002) diffraction peak for the porous ZnO nanorods was stronger than that of the as-grown ZnO nanorod. The PL intensity ratio of the near-band-edge emission (NBE) to the deep-level emission (DLE) of the porous ZnO nanorods was larger than that of the as-grown ZnO nanorods. In addition, as the average diameter of the pores increased, the PL intensity ratio of the porous ZnO nanorods gradually increased.