Ferroelectric Tunnel Junctions by Van Der Waals Sliding
Ferroelectric tunnel junction that endure multiple operations without degradations.
Ferroelectric memories can indeed operate fast at GHz frequencies, yet operating at such speeds for ~ 10 years suggests 1016 operations. Current ferroelectric memories degrade much earlier (after ~ 107 operations), and hence are limited for use in future memory and computation applications.
OUR SOLUTION
Ferroelectric tunnel junction that rely on a fundamentally different switching mechanism, made of a highly inert layered dielectric crystal – hexagonal boron nitride (hBN).
We recently discovered a permanent electric polarization in a particular stacking configuration of two layers made of hBN (each layer is one atom thick). Switching the interfacial polarization is achieved by a lateral sliding between the layers by one interatomic spacing. Unlike common non-layered ferroelectric systems, it only involves the motion of atoms which are weakly bond by van der Waals attraction between the two layers. Within each layer, however, the atoms form tight bonds making the hBN crystal one of the most stable, inert, and stiff materials in nature.
ADVANTAGES
Our discovery of ultimately thin ferroelectricity (only two-atoms thick), demonstrate a large tunneling currents at small bias voltages, which should translate into a very fast and efficient reading operations.
The spontaneous electric field is highly confined to the interface, on a 1 nm scale. Hence, it is expected to support the squeezing of multiple bits per area, far beyond current systems where inter-domain couplings limit their density. The hBN crystal is known for a record high heat conductivity and hence expected to allow much faster reading and writing operations.
APPLICATIONS
New non-volatile memories.