Effect of annealing temperature on the microstructure and optoelectronic properties of niobium-doped anatase TiO2 thin films grown on soda-lime glass substrate

In this work, we report on the growth of high-quality transparent conducting niobium-doped anatase TiO2 (NTO) thin film on soda-lime glass substrate (SLG) by altering the annealing temperature. To this end, NTO films (with a thickness of ~131 nm) are deposited on SLG substrates at room temperature by radio frequency (RF) magnetron sputtering, following which these films are subjected to the post-deposition annealing at temperatures (T) in the range of 623 to 1023 K for 1 h at ~2.2 × 10–4 Pa. The crystallinity of these NTO films is considerably altered with T, which is found to effect significantly their overall optoelectronic properties. NTO film fabricated at T of 823 K exhibited the lowest electrical resistivity of 9.84 × 10–3 Ω cm (with carrier concentration of 0.74 × 1021 cm–3 and carrier mobility of 0.85 cm2 V–1 s–1) and an average visible transmittance of ~76%. Apart from developing an understanding on the role of annealing temperature on the microstructural, optical and electrical properties of NTO films, this study also realized the growth of high-quality NTO film on the cost-effective SLG substrate.