Effect of the Precursor Solution Concentration of CuI Thin Film Deposited by Spin Coating Method

In this research, the effect of precursor concentration of CuI thin film deposited by spin coating method was studied. The wide band gap p-type semiconductor CuI thin film was prepared by mixing the CuI powder with 50 ml of acetonitrile as a solvent. The CuI concentration varies from 0.05M to 0.5M. The speed for spin coating is 1000 rpm for 60 seconds. After the deposition the CuI thin films were annealed at 150°C. The result shows the CuI thin film properties strongly depends on its precursor concentration. Thickness between 33.65 nm - 441.25 nm was obtained as the concentration increased. The increment of thickness affected the electrical property with resistivity of about 10-6 Ω.cm and 101 Ω.cm was observed for all the CuI thin films. For optical properties, the transmittance decreased with high concentration as high amount of CuI particle were observed in the thin films. From the transmittance, the absorption coefficient of 10-6 m-1 and optical band gap of 3.10 and 3.50 eV for all the films were observed using Tauc’s plot.