Formation of indium-doped zinc oxide thin films using chemical spray techniques: The importance of acetic acid content in the aerosol solution and the substrate temperature for enhancing electrical transport

Indium-doped zinc oxide (ZnO:In) thin films were grown on glass substrates using the chemical spray technique. The effects of the acetic acid content in the starting solution (c _AA), as well as the substrate temperature (T _S), were studied. Our results demonstrate that when c _AA is extremely low, the resistivity values of the zinc oxide (ZnO) thin films become relatively high (in the order of 4 × 10 ^{- 2} Ω cm). When the c _AA is increased at a fixed temperature, the resistivity of the films decreases, reaching values as low as 4 × 10 ^{- 3} Ω cm for thin films deposited at 525 °C. The electron mobility could also increase to a maximum value of 10.5 cm ²/(V s) for films deposited at 500 °C. We also observed an enhancement in the electrical transport properties of the films by varying T _S; the lowest resistivity values occurred in films deposited at T _S between 475 and 525 °C. In addition, the relative intensity of the diffraction peaks associated with the crystallographic planes is strongly affected by the c _AA concentration. X-ray diffraction studies reveal the polycrystalline nature of the films exhibiting a hexagonal wurtzite type, with a preferential orientation of the film depending on the acetic acid concentration. Film morphology was also affected by varying c _AA, as grains with distinct geometrical shapes were observed. Finally, the optical transmittance of all these films was found to be higher than 85%.