Structural, Optical, and Magnetic Properties of Cobalt-Doped Dip Coated ZnO Films

Co-doped zinc oxide thin films (ZnCoO) have been deposited on glass substrates by sol-gel dip coating deposition method. X-ray diffractometer patterns for these thin films prove crystalline behavior with wurtzite structure. The films have lattice parameters similar to that of ZnO. When Zn is replaced by Co, more impurity levels are produced within the bandgap, and more defects are developed. However, Co-doping does not alter the wurzite structure. The bandgap of the films tends to decrease with increasing withdrawal speed. These transparent thin films possess bandgap in the ultra-violet (3.86-3.45 eV) and high transparency throughout the visible spectral region. Ellipsometry also show the same trend for bandgaps (3.83-3.45). Morphological analysis by scanning electron microscope shows surface with porous structure. Magnetic property studied shows the ferromagnetic behavior. Chemical composition of these Co-doped ZnO thin films was investigated through Fourier transform infrared analysis.