Transparent conductive CuI thin films prepared by pulsed laser deposition

Abstract Cuprous iodide (CuI) thin films were prepared by a pulsed laser deposition (PLD) technique, and the effects of the laser energy and substrate temperature on the structure and optical–electrical properties were investigated by X‐ray diffraction (XRD), scanning electronic microscopy (SEM), transmittance spectra, and resistivity measurements. At a substrate temperature of room temperature (RT), thin films include highly crystallized and (111)‐orientation preferred γ‐CuI and trace I 2 O 5 phases, and have resistivity of the order of 10 −1 Ω cm, average transmittance of about 80% at 410–1000 nm, and the bandgap ( E g ) of 3.01 eV at different laser energies. At the same laser energy of 250 mJ/pulse, phase structure, and E g of the films are uniform as substrate temperature increases to 350 °C, but the resistivity increases to the order of 1 Ω cm and the average transmittance decreases to 60%; the structure and properties of the films completely change as substrate temperature increases to 500 °C. The XRD and transmittance spectra analysis indicate that rudimental oxygen is introduced into CuI thin films, which results in obviously lower resistivity than that of the previously reported value (10 3 Ω cm). These results imply that the prepared CuI films exhibit excellent transparent conductive properties and can be used in solar cells.