ABSTRACTWe report on the use of La₂O₃ (LO) as a capping layer for ferroelectric-gate thin-film transistors (FGTs) with solution-processed indium-tin-oxide (ITO) channel and Pb(Zr,Ti)O₃ (PZT) gate insulator. The fabricated FGT exhibited excellent performance with a high “ON/OFF” current ratio (I_ON/I_OFF) and a large memory window (∆V_th) of about 10⁸ and 3.5 V, respectively. Additionally, a significantly improved data retention time (more than 16 hours) as compared to the ITO/PZT structure was also obtained as a result of good interface properties between the ITO channel and LO/PZT stacked gate insulator. We suggest that the LO capping layer acts as a barrier to prevent the interdiffusion and provides atomically flat ITO/LO/PZT interface. This all-oxide FGT device is very promising for future ferroelectric memories.