High-Performance Amorphous InGaZnO Thin-Film Transistor Gated by HfAlOₓ Dielectric With Ultralow Subthreshold Swing
Li Zhu, Yongli He, Chunsheng Chen, Xiangjing Wang, Ying Zhu, Yixin Zhu, Huiwu Mao, Changjin Wan, Qing Wan
Abstract
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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> . 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{\text{ON}}/I_{\text{OFF}}$ </tex-math></inline-formula> and a high mobility of 2.76 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 10^{{9}}$ </tex-math></inline-formula> and 18.94 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}\cdot \text{s}$ </tex-math></inline-formula> 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.