High quality ITO thin films for application as conductive transparent electrodes

A detailed study of structural, electrical and optical properties of ITO films, obtained under various deposition conditions by RF sputtering in pure Ar gas atmosphere, has been performed. The relationship between sheet resistance and optical transmittance of the films studied was followed through the variation of sputtering voltage, substrate temperature and film thickness. The figure of merit of these films, which is a measure of their quality as transparent conductive electrode, was evaluated. It is established that the deposition of ITO films at higher sputtering voltages leads to a considerably lower sheet resistance, better optical transparency and lower roughness of the films. The investigation of the film microstructure by X-ray diffraction (XRD) analysis showed that the prepared ITO films are polycrystalline with preferred (111) orientation. The AFM study performed revealed the formation of smooth films at higher V-s, with nanosized grains and uniformally distributed electrical current. Besides, smooth uniform ITO films with low resistance of 8 Omega/sq and average transmittance above 82% in the visible range 400-800nm were obtained on glass substrates without additional annealing of films. Thus, the possibilities of producing high quality ITO films by the RF sputtering method used at the established optimal experimental conditons have been demonstrated.