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 I2O5 phases, and have resistivity of the order of 10-1 Ω cm, average transmittance of about 80% at 410-1000 nm, and the bandgap (Eg) of 3.01 eV at different laser energies. At the same laser energy of 250 mJ/pulse, phase structure, and Eg 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 (103 Ω cm). These results imply that the prepared CuI films exhibit excellent transparent conductive properties and can be used in solar cells. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.