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

Abstract

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 (cAA), as well as the substrate temperature (TS), were studied. Our results demonstrate that when cAA 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 cAA 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 cm2/(V s) for films deposited at 500 °C. We also observed an enhancement in the electrical transport properties of the films by varying TS; the lowest resistivity values occurred in films deposited at TS between 475 and 525 °C. In addition, the relative intensity of the diffraction peaks associated with the crystallographic planes is strongly affected by the cAA 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 cAA, as grains with distinct geometrical shapes were observed. Finally, the optical transmittance of all these films was found to be higher than 85%.