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

In this paper, we compared the structural and electrical properties of high- κ Gd
₂
O
₃
and GdTiO
₃
gate dielectrics for an amorphous indium-gallium-zinc oxide ( α-IGZO) thin-film transistor (TFT) application. In comparison with the Gd
₂
O
₃
dielectric, the α-IGZO TFT featuring the GdTiO
₃
dielectric exhibited better electrical characteristics in terms of a large field effect mobility of 26.9 cm
²
/Vs, a low threshold voltage of 0.04 V, a high ION/IOFF ratio of 1.2×10
⁸
, and a low subthreshold swing of 200 mV/decade. We attribute these results to the incorporation of Ti into the Gd
₂
O
₃
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 Gd
₂
O
₃
and GdTiO
₃
a-IGZO TFTs was studied under positive gate bias stress.