High performance and high stability low temperature aqueous solution-derived Li–Zr co-doped ZnO thin film transistors

Abstract

Highly stable and high performance solution-processed amorphous oxide semiconductor thin film transistors (TFTs) were produced using a Li and Zr co-doped ZnO-based aqueous solution. Li and Zr co-doping at the appropriate amounts enhanced the oxide film quality in terms of enhanced oxygen bonding and reduced defect sites. The 0.5 mol% Li and 1.0 mol% Zr co-doped ZnO TFTs annealed at 320 °C exhibited noticeably lower threshold voltage shifts of 3.54 V under positive bias stress and −2.07 V under negative bias temperature stress than the non-doped ZnO TFTs. The transistors revealed a good device mobility performance of 5.39 cm² V⁻¹ s⁻¹ and an on/off current ratio of 10⁸ when annealed at 320 °C, compared to a mobility performance of 2.86 cm² V⁻¹ s⁻¹ and an on/off current ratio of ∼10⁷ when annealed at 270 °C. Our results suggest that Li and Zr co-doping can be a useful technique to produce more reliable and low temperature solution-processed oxide semiconductor TFTs.