Improving Thermal Stability of Solution Process Indium Zinc Oxide Thin Film Transistors by Praseodymium Oxide Doping.

Praseodymium-doped indium zinc oxide (PrIZO) channel materials have been fabricated by a solution process with conventional chemical precursor. The PrIZO based thin film transistors -(TFTs) exhibited a field effect mobility of 10.10 cm/Vs, a sub-threshold swing (SS) value of 0.25 V/decade, and an Ion/Ioff ratio of 10. The as-fabricated PrIZO-TFTs showed improved device performance against positive bias temperature stress (PBTS shift of 1.97 V for 7200 s), which was evidently better than the undoped IZO-TFTs (PBTS shift of 9.52 V). This result indicates that the organic residual (-OCH and -CH-) in metal oxide semiconductor, which is confirmed to be dominant effect on the performance of PBTS, can be passivated by the rare earth of praseodymium element. The residual is intended to be oxidized with a more stable ester group with the assistant of PrOx, weakening the electron-withdrawing characteristic during thermal bias stress.