Effects of zirconium doping on the characteristics of tin oxide thin film transistors

Thin-film transistors (TFTs) with zirconium-doped tin oxide (ZSO) channels were fabricated by co-sputtering Sn and Zr metal targets. The effect of Zr on the performance of SnOx-based TFTs was studied. TFTs with an intrinsic SnOx channel did not show promising performance. However, ZSO TFTs exhibited improved electrical properties, with increased ION/IOFF and decreased subthreshold swing. The influence of zirconium doping on bias stability in tin oxide TFTs was also investigated. ZSO TFTs exhibited turn-on voltage (VON) shifts of +9 V for positive stress bias, compared with +18 V for intrinsic SnOx TFTs. The improvements in device performance and stability were attributed to reduced carrier concentration induced by carrier trapping at Zr impurity sites.