Electrical and Reliability Characteristics of High- $\kappa~{\rm HoTiO}_{3}~\alpha$-InGaZnO Thin-Film Transistors

In this letter, we investigated the electrical and reliability characteristics of high- κ HoTiO
₃
amorphous indium-gallium-zinc oxide ( α-IGZO) thin-film transistor (TFT) devices. The α-IGZO TFT device incorporating an HoTiO
₃
dielectric exhibited excellent electrical characteristics in terms of a low threshold voltage of 0.12 V, a high field-effect mobility of 21.4 cm
²
/V
_s
, a small subthreshold swing of 160 mV/decade, and a high I
_ON
/I
_OFF
current ratio of 1.3 ×10
⁸
. These results are attributed to the incorporation of TiO
_x
into the Ho
₂
O
₃
film forming the smooth surface roughness and thus reducing the oxygen vacancies. Furthermore, the threshold voltage stability of HoTiO
₃
α-IGZO TFT was studied under both positive and negative bias stress conditions.