Preparation and characteristics of Nb-doped indium tin oxide thin films by RF magnetron sputtering

Niobium-doped indium tin oxide (ITO:Nb) thin films are fabricated on glass substrates by radio frequency (RF) magnetron sputtering at different temperatures. Structural, electrical and optical properties of the films are investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible (UV-VIS) spectroscopy and electrical measurements. XRD patterns show that the preferential orientation of polycrystalline structure changes from (400) to (222) crystal plane, and the crystallite size increases with the increase of substrate temperature. AFM analyses reveal that the film is very smooth at low temperature. The root mean square (RMS) roughness and the average roughness are 2.16 nm and 1.64 nm, respectively. The obtained lowest resistivity of the films is 1.2×10^?4Ω·cm, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 16.5 cm²/V·s and 1.88×10²¹cm^?3, respectively. Band gap energy of the films depends on substrate temperature, which is varied from 3.49 eV to 3.63 eV.