Structure, optical and electrical properties of Nb-doped ZnO transparent conductive thin films prepared by co-sputtering method

Nb-doped ZnO thin films were fabricated on glass substrates by using co-sputtering with direct-current and radio frequency magnetron sputtering. The structures, optical and electrical performances of Nb-doped ZnO thin films were investigated. The results showed that all thin films have (0 0 2) c-axis preferential orientation. The minimum resistivity of 2.12 x 10(-3) Ocm and the maximum carrier concentration of 2.39 x 10(19) cm(-3) were obtained at the direct-current sputtering power of 10W, respectively. Nb-doped ZnO thin films have also shown high average transmittance of 89.6%, and lower surface roughness of 2.74 nm. Meanwhile, a distinct absorption edge in the ultraviolet range of 300-400 nm was observed in absorbance, the optical band gap of Nb-doped ZnO thin films illustrates an increased tendency with increasing Nb concentration.