Comparison of High- $\kappa ~{\rm Gd}_{2}{\rm O}_{3}$ and ${\rm GdTiO}_{3}~\alpha$ -InGaZnO

In this paper, we compared the structural and electrical properties of high- κ Gd₂O₃ and GdTiO₃ gate dielectrics for an amorphous indium-gallium-zinc oxide ( α-IGZO) thin-film transistor (TFT) application. In comparison with the Gd₂O₃ dielectric, the α-IGZO TFT featuring the GdTiO₃ dielectric exhibited better electrical characteristics in terms of a large field effect mobility of 26.9 cm²/Vs, a low threshold voltage of 0.04 V, a high ION/IOFF ratio of 1.2×10⁸, and a low subthreshold swing of 200 mV/decade. We attribute these results to the incorporation of Ti into the Gd₂O₃ film, forming a smooth surface and thus reducing density of interface states at the oxide/channel interface. In addition, the stability of threshold voltage on high- κ Gd₂O₃ and GdTiO₃ a-IGZO TFTs was studied under positive gate bias stress.