Growth and characterization of sol–gel prepared Gd2O3 films as gate insulators for Zn–Sn–O thin film transistors

• Solution processed high-k Gd2O3 gate insulator for oxide thin film transistors (TFTs)
• Low voltage-operated TFTs with enhanced switching property can be obtained.
• Sol–gel prepared lanthanide films can be applicable to printing-based TFTs.

A solution-processed oxide thin film transistor (TFT) with low operating voltage is demonstrated using a high dielectric constant Gd2O3 gate insulator. Prepared using spin coating followed by annealing at 400 °C, the Gd2O3 film exhibits a dielectric constant in the range of 10–12 with a breakdown field as high as 3.5 MV cm− 1. A proper amount of polymeric agent, polyvinylpyrrolidone (PVP), is very important to access uniform film growth, a smooth surface morphology, and a low leakage current, while the annealing temperature and film thicknesses are important as well for the operational solution-processed gate insulator. The resultant Zn–Sn–O/Gd2O3 TFT exhibits enhanced performance with a field-effect mobility of ~ 2.53 cm2V− 1 s− 1 by a factor of 8.7 compared with the TFTs using a SiO2 insulator with an exceptionally low operating voltage < 10 V.