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(Nanowerk News) As electronic devices get progressively smaller, the technology that powers them needs to get smaller and thinner.
One of the key challenges scientists face in developing this technology is finding materials that can work well in an ultrathin size. But now, Berkeley researchers think they may have the answer.
Led by Sayeef Salahuddin, professor of electrical engineering and computer science, and graduate student Suraj Cheema, a team of researchers has managed to develop silicon, an ultrathin material that demonstrates a unique electrical property called ferroelectricity. The duo’s findings were published in the April 22 issue of Nature (“Improved ferroelectricity in ultrathin films grown directly on silicon”).
Ferroelectricity refers to a class of materials that can not only achieve spontaneous electrical polarization, but also reverse direction when exposed to an external electric field, which is promising for electronics.
The team’s advance demonstrates the ferroelectric effects on a material just 1 nanometer thick, equivalent to the size of just two atomic building blocks. As a result, the material can efficiently power smaller devices with lesser amounts of energy.
“We are making computing devices that are getting smaller and smaller,” Salahuddin said. “You don’t want to use thick materials because you don’t have space. With our ferroelectric material, you really don’t need to worry about space.”
Previously, researchers had successfully stabilized ferroelectricity in increasingly thinner materials. But below around 3 nanometers, “ferroelectricity decreases in conventional ferroelectric materials,” Cheema said.
Until now. The Berkeley team cultured a nanometer-thick doped hafnium oxide on silicon. Not only did the ultrathin material demonstrate ferroelectricity, but the effect was actually stronger than the multi-nanometer-thick material, a “fundamental breakthrough” in the field of ferroelectricity, Salahuddin said.
The finding could lead to the creation of more advanced batteries and sensors. But the work is particularly promising for memory and logic chips in computers.
The discovery of ferroelectricity in films only 1 nanometer thick means that these storage cells could be reduced to smaller dimensions than previously thought possible.
“We can grow ferroelectric materials that can be used in making computer chips today,” said Salahuddin.
