A critical study of the optical and electrical properties of transparent and conductive Mo-doped ZnO films by adjustment of Mo concentration

Mo-doped zinc oxide (ZnO: Mo) transparent conductive thin films were prepared on the glass substrates using simple chemical spray pyrolysis technique by varying the Mo doping concentration in the range, 0-5 at.% at a constant substrate temperature, 400 degrees C. The effect of Mo-doping concentration on the physical behavior of ZnO films was investigated. The X-ray Photoelectron Spectroscopy (XPS) analysis confirmed the presence of Zn, O, and Mo in the layers with Mo in +6 state. The X-ray diffraction (XRD) patterns exhibited hexagonal wurtzite crystal structure without any secondary phases. The microstructural analysis revealed the spherical nut-shaped grains over the substrate surface. The optical studies revealed that the films with Mo-doping concentration of 2 at.% showed high optical transmittance and a wide band gap than pure and highly Mo-doped ZnO films. From the optical transmittance versus wavelength data, the refractive index, extinction coefficient, dispersion constants were evaluated. In addition, other optical parameters such as the optical conductivity, dielectric constants, dissipation factor, electron energy loss functions and Haze were also calculated. The FTIR studies revealed the presence of modes related to ZnO. Finally the electrical parameters such as resistivity, charge carrier mobility and density of ZnO: Mo films were also analyzed and presented.