Study on the Structure,Optical and Electrical Properties of Nb Doped ZnO Transparent Conductive Thin Films

Highly conducting and transparent niobium doped zinc oxide(NZO) thin films had been deposited by DC magnetron sputtering method on glass substrates.Five samples with thickness of 239 nm,355 nm,489 nm,575 nm and 679 nm are used for the analysis of film thickness effect.XRD studies show that the ZnO∶ Nb films are polycrystalline with the hexagonal structure and have preferred orientation with the c axis perpendicular to the substrates.The crystallinity of the films improved significantly as the thickness increasing.As the thickness increasing from 239 nm to 489 nm,the mean crystallite size increases from 19.7 nm to 24.7 nm and the resistivity decreases continuously.As the thickness increasing further,the crystallite size shows a little decrease and the resistivity increases a little.The lowest resistivity obtained is 4.896×10-4 Ω·cm in this experiment.The optical band gap initially increases and then decreases when the film thickness increases.All the films present a transmittance of above 88.3% in the wavelength range of the visible spectrum.