Enhanced polarization switching characteristics of HfO2 ultrathin films via acceptor-donor co-doping

TL;DR

This paper demonstrates that acceptor-donor co-doping in HfO2 ultrathin films significantly enhances ferroelectricity and switching speed, enabling ultrathin devices with improved performance for ferroelectric memory applications.

Contribution

The study introduces a co-doping strategy with La3+ and Ta5+ to improve ferroelectric switching characteristics of HfO2 films, achieving record-fast switching among HfO2 devices.

Findings

Enhanced ferroelectricity in co-doped HfO2 films.

Achieved the fastest switching process reported for HfO2.

Maintained robust electrical properties at 3 nm thickness.

Abstract

In the realm of ferroelectric memories, HfO2-based ferroelectrics stand out because of their exceptional CMOS compatibility and scalability. Nevertheless, their switchable polarization and switching speed are not on par with those of perovskite ferroelectrics. It is widely acknowledged that defects play a crucial role in stabilizing the metastable polar phase of HfO2. Simultaneously, defects also pin the domain walls and impede the switching process, ultimately rendering the sluggish switching of HfO2. Herein, we present an effective strategy involving acceptor-donor co-doping to effectively tackle this dilemma. Remarkably enhanced ferroelectricity and the fastest switching process ever reported among HfO2 polar devices are observed in La3+-Ta5+ co-doped HfO2 ultrathin films. Moreover, robust macro-electrical characteristics of co-doped films persist even at a thickness as low as 3 nm, expanding potential applications of HfO2 in ultrathin devices. Our systematic investigations further demonstrate that synergistic effects of uniform microstructure and smaller switching barrier introduced by co-doping ensure the enhanced ferroelectricity and shortened switching time. The co-doping strategy offers an effective avenue to control the defect state and improve the ferroelectric properties of HfO2 films.