Controller of Fluorinedoped Tin Oxide Thin Films Deposition via Cycles and Annealing Temperatures by Spin Coating Techniques

Abstract

Fluorine-doped tin oxide (FTO) thin films have been deposited by the modified spin coating method at 3000 rpm using tin (II) chloride dehydrate (SnCl2×2H2O) as a precursor, ammonium fluoride (NH4F) as a dopant and ethanol as a solvent. The aim of this research is to find out the quality of the thin film based on the number of cycles (3, 4, 5, and 6 cycles) and annealing temperature (300, 400 and 500 °C). The variation of annealing temperature and number of cycles can affect the crystal structure of the FTO thin film, crystal size and grain size. Increasing the number of cycles and annealing temperature can lead to larger crystallite size and lower dislocation density, so that electrons between the grains can move easily. The large grain can reduce the grain boundary, increasing the electron mobility and decreasing the resistivity. XRD analysis shows that the structure of SnO2 polycrystalline with the most dominant crystal plane (110) is formed in this research when compared to the intensity of other structures. The resistivity value decreases with increasing the annealing temperature and number of cycles. In addition, transparency value also decreases along with increasing the annealing temperature and number of cycles. The optimum results of resistivity and transparency values obtained in this research are 1.692´10-2 Ω×cm and 69.232 % at 500 °C and 5 cycles. These results can be used as a reference for further study to optimize the production of fluorine-doped tin oxide (FTO) thin film with spin coating. Therefore, many factors that affect the production of fluorine-doped tin oxide (FTO) thin film, either dissolving stage or deposition process on the substrate surface still need to be studied deeply to obtain the optimum result.