Effects of Cobalt Doping on Optical Properties of ZnO Thin Films Deposited by Sol–Gel Spin Coating Technique
Subject Areas : Journal of Optoelectronical Nanostructures
Mahmood Borhani Zarandi
1
,
Hojjat Amrollahi Bioki
2
1 - Atomic and Molecular Group, Faculty of Physics, Yazd University, Yazd, Iran
2 - Department of Physics, Tarbiat Modares University, Tehran, Iran
Keywords: Sol-Gel, Optical Properties, Cobalt doped ZnO thin film,
Abstract :
Cobalt (Co) doped Zinc Oxide (ZnO) thin films, containing different amount
of Cobalt nanoparticles as the Co doping source, deposited by the sol–gel spin coating
method onto glass via annealing temperature at 400˚C, have been investigated by optical
characterization method. The effect of Co incorporation on the surface morphology was
clearly observed from scanning electron microscopy (SEM) images. Optical
conductivity and optical constants such as absorption coefficient, reflectivity, extinction
coefficient, and refractive index as a function of photon energy were calculated, and it
was found that the doping with Co led to decrease absorption coefficient, extinction
coefficient, refractive index and bandgap energy, while the optical conductivity
increased at higher photon energies. The optical band gap depends on the Co doping
level and on the particle size and crystallinity of the films and is in the range of 3.05–
3.17 eV. The optical band gap widening is proportional to the one-third power of the
carrier concentration.
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