An excellent review of the new field of 2D ferroelectric materials with layered van-der-Waals crystal structures, a novel class of low-dimensional materials that is particularly intriguing for future nanoelectronics, is provided by UNSW research that was recently published in Nature Reviews Materials.
Future uses could include flexible (energy-harvesting or wearable) electronics; high-performance, non-volatile data storage; high-response optoelectronics; and ultra-low energy electronics.
Standard van der Waals (vdW) ferroelectrics feature stable layered structures with a combination of strong intralayer and weak interlayer forces, which differ structurally from standard oxide ferroelectrics with rigid lattices.
Together with the ferroelectric order, these unusual arrangements of atoms create fundamentally new phenomena and abilities that are not found in traditional materials.
According to the author, Dr. Dawei Zhang, “Fundamentally novel properties are found when these materials are exfoliated down to atomically thin levels.” For example, unlike traditional ferroelectrics, the source of the polarization and the way the polar order can be changed can be different. This gives the material a unique way of working.
The weak van-der-Waals interlayer bonds in these materials make it easy to stack them. This means that vdW ferroelectrics can be easily combined with materials with very different crystal structures, like industrial silicon substrates, without any problems at the interfaces.
According to author Prof. Jan Seidel, who works at UNSW, “This makes them particularly interesting as building blocks for post-law Moore’s electronics.”
Due to their easily accessible nanoscale ferroelectricity and clean, bond-free vdW interfaces that make CMOS-compatible (current silicon technology) integration possible, vdW ferroelectrics offer a wide range of applications and new functions for nanoelectronics.
The newly released review talks about experimentally confirmed vdW ferroelectric systems and their distinctive features, like quadruple-well potentials, metallic ferroelectricity, and dipole-locking effects. It also includes centrosymmetrically broken stacks of nonpolar parent materials that show vdW ferroelectricity that has been designed.
Ingenious device applications that make use of vdW ferroelectricity are also highlighted, such as electronic transistors that surpass the basic thermodynamic constraints, non-volatile memories, and optoelectronic and flexible devices. Recent advancements and current difficulties provide perspective on upcoming research areas and applications.
According to author Dr. Pankaj Sharma, “It’s a relatively young field, so there are still many obstacles that need to be overcome to achieve the full technical potential of these materials.” For instance, we must discuss strategies for large-area, homogeneous wafer scale growth and integration. These will make it possible to create cutting-edge low-energy devices and computing systems.
Due to the vdW ferroelectrics’ recent development, the materials library for such systems is rapidly changing. New discoveries, including multiferroicity, coupled functions of multiple orders, like ferroelectricity and magnetism, and the operation of domain walls in such materials, are thus far possible.
