HfZrOₓ-Based Ferroelectric Tunnel Junction With Crested Symmetric Band Structure Engineering
Yilun Liu, Yuanyuan Cao, Hao Zhu, Ji Li, Lin Chen, Qingqing Sun, David Wei Zhang
Abstract
HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based ferroelectric tunnel junction (FTJ) devices have been studied as an attractive candidate in future CMOS-compatible ultra-low-power non-volatile memory techniques. However, the relatively low remnant polarization in the HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based thin films are still to be enhanced for further device implementation. Here, we propose an engineered FTJ device with crested symmetric band structure utilizing ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as the seed layer and capping layer to sandwich the Zr-doped HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (HZO) film. An ultra-thin Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> layer is inserted in HZO which further improves the remnant polarization reaching up to 24.2 μC/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The optimized FTJ devices exhibit larger tunneling electrical resistance ratio and higher read and write operation endurance. This illustrates a promising pathway to boost the ferroelectricity in HZO film by structure engineering and can be instructive for practical device applications.