Realizing multiple non-volatile resistance states in a two-dimensional domain wall ferroelectric tunneling junction

Nonvolatile Memory Device Based on the Ferroelectric Metal/Ferroelectric Semiconductor Junction

The ferroelectric tunnel junction (FTJ) is a competitive candidate for post-Moore nonvolatile memories due to its low power consumption and nonvolatility, with its performance being strongly dependent on the conditions for contact between the ferroelectric material and the metal electrode. The development of two-dimensional materials in recent years has offered new opportunities such as functional metal layers, which is challenging for traditional FTJ systems. Here, we introduce the newly discovered ferroelectric metal WTe2 as the electrode to construct WTe2/α-In2Se3/Au ferroelectric semiconductor junctions. The interplay between the ferroelectricity in the van der Waals electrode and tunnel junction leads to the emergence of novel device characteristics, including concomitant multiresistance levels, a low switching voltage (<2 V), and a high on/off ratio (>105). Using ferroelectric metal as the electrode for the ferroelectric tunnel/semiconductor junction offers an alternative approach to low-power and high-density ferroelectric memory devices.

The Integration of Two-Dimensional Materials and Ferroelectrics for Device Applications

In recent years, there has been growing interest in functional devices based on two-dimensional (2D) materials, which possess exotic physical properties. With an ultrathin thickness, the optoelectrical and electrical properties of 2D materials can be effectively tuned by an external field, which has stimulated considerable scientific activities. Ferroelectric fields with a nonvolatile and electrically switchable feature have exhibited enormous potential in controlling the electronic and optoelectronic properties of 2D materials, leading to an extremely fertile area of research. Here, we review the 2D materials and relevant devices integrated with ferroelectricity. This review starts to introduce the background about the concerned themes, namely 2D materials and ferroelectrics, and then presents the fundamental mechanisms, tuning strategies, as well as recent progress of the ferroelectric effect on the optical and electrical properties of 2D materials. Subsequently, the latest developments of 2D material-based electronic and optoelectronic devices integrated with ferroelectricity are summarized. Finally, the future outlook and challenges of this exciting field are suggested.