High-Performance Amorphous Indium Gallium Zinc Oxide Thin-Film Transistors With $\hbox{HfO}_{x}\hbox{N}_{y}/\hbox{HfO}_{2}/\hbox{HfO}_{x}\hbox{N}_{y}$ Tristack Gate Dielectrics

We have fabricated and investigated amorphous indium gallium zinc oxide (α-IGZO) thin-film transistors (TFTs) by using HfO
_x
N
_y
/HfO
₂
/HfO
_x
N
_y
(NON) as the gate dielectric. The NON tristack dielectric structure can increase the gate capacitance density, effectively improve interface properties of both the gate/dielectric and dielectric/active channels, suppress the charge trap density, and reduce the gate leakage. The α-IGZO TFT (W/L = 200/10 μm) with NON shows superior performance such as a saturation current of 0.33 mA, an ON/OFF-current ratio of 2.2 × 10
⁶
, a saturation mobility of 10.2 cm
²
/V · s, a source/contact resistivity of 83 Ω · cm, a subthreshold swing of 0.13 V/dec, and enhanced stressing reliability.