Thinnest ferroelectric material helps to produce new energy-efficient devices, researchers claim
New energy-efficient devices are made possible by the thinnest ferroelectric material ever created, thanks to the University of California Berkeley and Argonne National Laboratory.
As a result of this development, intriguing material behavior at small scales could reduce energy demands for computing, revealed ANL.
The Department of Energy's (DOE) Argonne National Laboratory has discovered a solution that overcomes both difficulties at the same time by fabricating the thinnest ferroelectric ever reported as well as the thinnest demonstration of working memory on silicon.
At the University of California at Berkeley, researchers also did experiments and shared the results in the journal Science.
What's the deal with ferroelectrics?
As per ANL, Ferroelectrics, a class of advanced materials, offers a promising way to reduce the power used by the ultrasmall electronic components found in computers and cell phones. However, below a few nanometers in thickness, ordinary ferroelectric materials lose their internal polarization. This indicates that they are incompatible with silicon technology used today. Ferroelectrics had historically been unable to be integrated into microelectronics due to this problem.
200,000 times thinner than human hair
The researchers observed stable ferroelectricity in a half-nanometer-thick layer of zirconium dioxide. That is the size of a single atomic building block, which is approximately 200,000 times thinner than human hair. This material was grown directly on silicon by the team.
They discovered ferroelectricity in zirconium dioxide, which is generally a non-ferroelectric material when it is grown exceedingly thin, about 1-2 nanometers in thickness.
The researchers were also able to use a modest voltage to alter the polarization of this ultrathin material back and forth, enabling the thinnest demonstration of a functioning memory ever reported on silicon. It also holds significant promise for energy-efficient electronics, especially given that ordinary zirconium dioxide is already included in today's cutting-edge silicon chips.
“This work takes a key step towards integrating ferroelectrics into highly scaled microelectronics,” said Suraj Cheema, a postdoctoral researcher at UC Berkeley, the first author of the study.
Squeezing 3D materials to the 2D thickness
This work has important implications for creating new two-dimensional materials in addition to its immediate technological significance.
“Simply squeezing 3D materials to their 2D thickness limit offers a straightforward-yet-effective route to unlocking hidden phenomena in a wide variety of simple materials,” Cheema said.
“This greatly expands the materials design space for next-generation electronics to include materials already compatible with silicon technologies.”
This work was led by Cheema and Sayeef Salahuddin of UC Berkeley, along with co-first authors Nirmaan Shanker and Shang-Lin Hsu.
The critical size limit of voltage-switchable electric dipoles has extensive implications for energy-efficient electronics, underlying the importance of ferroelectric order stabilized at reduced dimensionality. We report on the thickness-dependent antiferroelectric-to-ferroelectric phase transition in zirconium dioxide (ZrO2) thin films on silicon. The emergent ferroelectricity and hysteretic polarization switching in ultrathin ZrO2, conventionally a paraelectric material, notably persists down to a film thickness of 5 angstroms, the fluorite-structure unit-cell size. This approach to exploit three-dimensional centrosymmetric materials deposited down to the two-dimensional thickness limit, particularly within this model fluorite-structure system that possesses unconventional ferroelectric size effects, offers substantial promise for electronics, demonstrated by proof-of-principle atomic-scale nonvolatile ferroelectric memory on silicon. Additionally, it is also indicative of hidden electronic phenomena that are achievable across a wide class of simple binary materials.
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