An approach to the description of the correlation between the electrical conductivity and the band gap of F-doped zinc oxide thin films

The ultrasonic spray method was applied to investigate fluorine-doped zinc oxide thin films on glass substrate at 420 °C, with different fluorine doping rates ranging from 0 to 5 at%. This study presents a new description of the relationship linking the electrical conductivity to the optical band gap with various fluorine doping levels. It was found that all films exhibited high electrical conductivity values. The highest electrical conductivity was found equal to 169 (Ωcm)⁻¹; this was obtained for the 5 at% doping level. Moreover, it turned out that the optical band gap dropped from 3.39 to 3.28 eV as the fluorine doping level augmented. The correlation between the electrical and optical properties and the doping level suggests that the optical band gap and fluorine doping level have a significant impact on the electrical conductivity of the thin films under consideration. In addition, the equation correlating the electrical conductivity and the doping level gave a maximum error of about 4% for fluorine-doped zinc oxide for a concentration of 3 at%. However, the experimental results for the correlation between the electrical conductivity and the fluorine doping level of ZnO films turned out to be invariable.