High-Performance Amorphous InGaZnO Thin-Film Transistor Gated by HfAlOₓ Dielectric With Ultralow Subthreshold Swing

We report a high-performance transparent amorphous indium gallium zinc oxide thin-film transistor (a-IGZO TFT) gated by atomic layer deposition (ALD)-deposited HfAlO
_x
. Through a postfabrication annealing optimization process, the total trap density of the device can be reduced in two orders of magnitudes. The subthreshold swing (SS) reaches an ultralow level of 62.29 mV/dec due to the low defect states. A large
$I_{\text{ON}}/I_{\text{OFF}}$
and a high mobility of 2.76
$\times 10^{{9}}$
and 18.94 cm
²
/
$\text{V}\cdot \text{s}$
can be achieved, respectively. In addition, the devices exhibit good stability in terms of positive bias stress, thermal, and aging tests. The defect optimization process has been verified by the X-ray photoelectron spectroscopy analysis. Finally, a resistor-loaded inverter was constructed, which showed ideal swing characteristics and its voltage gain was as high as 39 at 7 V. These results indicate such a-IGZO TFT is of great potential for the emerging electronics, large-area display, and other low-power electronics.