The new technology, which enables the storage of information in the tiniest unit known to science, is projected to improve future electronic gadgets’ density, speed, and efficiency.
- The technology involves sliding one-atom-thick layers of boron and nitrogen one over the other – a new way to switch electric polarization on/off.
Tel Aviv University researchers have created the world’s thinnest technology, with a thickness of only two atoms. The new technology, which published in Science magazine, can store electric information in the tiniest available unit in the most stable and inert substance in the world. By using quantum-mechanical electron tunneling, it may improve the reading of information much beyond present technology.
Current technologies include crystals with less than a million atoms (about 100 atoms high, wide, and thick) that can be compressed one million times into the size of one coin with each device switching at a speed of a million times per second.
The breakthrough in technology enabled the researchers to lower the thickness of the crystalline devices to two atoms. Dr. Ben Shalom stresses that a low-density molecular structure aids electrons in quickly and effectively hopping through obstacles that are just a few atoms thick. So as a result, the use of electronic gadgets can be substantially improved.
“Our research stems from curiosity about the behavior of atoms and electrons in solid materials, which has generated many of the technologies supporting our modern way of life,” says Dr. Ben Shalom. “We (and many other scientists) try to understand, predict, and even control the fascinating properties of these particles as they condense into an ordered structure that we call a crystal. At the heart of the computer, for example, lies a tiny crystalline device designed to switch between two states indicating different responses – “yes” or “no”, “up” or “down” etc.
“Without this dichotomy – it is not possible to encode and process information. The practical challenge is to find a mechanism that would enable switching in a small, fast, and inexpensive device,” says Dr. Ben Shalom.
Researchers employed a two-dimensional material: one-atom-thick layers of boron and nitrogen, in a repeated hexagonal arrangement. In their experiment, they were able to break the symmetry of this crystal by artificially assembling two such layers.
“In its natural three-dimensional state, this material is made up of a large number of layers placed on top of each other, with each layer rotated 180 degrees relative to its neighbors (antiparallel configuration)” says Dr. Ben Shalom. “In the lab, we were able to artificially stack the layers in a parallel configuration with no rotation, which hypothetically places atoms of the same kind in perfect overlap despite the strong repulsive force between them (resulting from their identical charges). In actual fact, however, the crystal prefers to slide one layer slightly in relation to the other, so that only half of each layer’s atoms are in perfect overlap, and those that do overlap are of opposite charges – while all others are located above or below an empty space – the center of the hexagon. In this artificial stacking configuration the layers are quite distinct from one another. For example, if in the top layer only the boron atoms overlap, in the bottom layer it’s the other way around.”
The Ph.D. student who led the study, Maayan Wizner Stern, explains: “The symmetry breaking we created in the laboratory, which does not exist in the natural crystal, forces the electric charge to reorganize itself between the layers and generate a tiny internal electrical polarization perpendicular to the layer plane. When we apply an external electric field in the opposite direction the system slides laterally to switch the polarization orientation. The switched polarization remains stable even when the external field is shut down. In this, the system is like thick three-dimensional ferroelectric systems, which are widely used in technology today.”
Vizner Stern concludes: “We are excited about discovering what can happen in other states we force upon nature and predict that other structures that couple additional degrees of freedom are possible. We hope that miniaturization and flipping through sliding will improve today’s electronic devices, and moreover, allow other original ways of controlling information in future devices. In addition to computer devices, we expect that this technology will contribute to detectors, energy storage and conversion, interaction with light, etc. Our challenge, as we see it, is to discover more crystals with new and slippery degrees of freedom.”
The research team included scientists from the Raymond and Beverly Sackler School of Physics and Astronomy and Raymond and Beverly Sackler School of Chemistry. The group includes Maayan Vizner Stern, Yuval Waschitz, Dr. Wei Cao, Dr. Iftach Nevo, Prof. Eran Sela, Prof. Michael Urbakh, Prof. Oded Hod, and Dr. Moshe Ben Shalom.