|Dec 17, 2019|
Researchers close in on new nonvolatile memory(Nanowerk News) Researchers from the Moscow Institute of Physics and Technology, along with their colleagues from Germany and the U.S., have achieved a breakthrough on the way to new types of nonvolatile memory devices. The team came up with a unique method for measuring the electric potential distribution across a ferroelectric capacitor -- the device underlying the memory of the future, which would be orders of magnitude faster than the current flash and solid-state drives, withstanding 1 million times as many rewrite cycles.
|The paper was published in Nanoscale ("Polarization-dependent electric potential distribution across nanoscale ferroelectric Hf0.5Zr0.5O2 in functional memory capacitors").|
|Electronics companies worldwide pursue new nonvolatile memory technologies to enable vastly faster access speeds and longer lifetimes compared with the flash and solid-state drives of today. One of the leading contenders is hafnium dioxide-based memory. The material it uses is a dielectric already known to the microelectronics industry.|
|Subjected to certain temperature treatment and alloying, a few nanometer-thick hafnium dioxide layer can form metastable crystals that possess ferroelectric properties -- that is, they "remember" the direction of the electric field applied to them.|
|The new memory cell is a zirconium-hafnium oxide film merely 10 nanometers thick, interlaid between two electrodes. Its structure resembles a conventional electric capacitor.|
|To make ferroelectric capacitors usable as memory cells, their remnant polarization has to be maximized; and to ensure that, engineers need a detailed understanding of the processes that occur in the nanofilm. This involves explaining how the electric potential is distributed across the film following voltage application and polarization reversal.|
|Since the discovery of a ferroelectric phase in hafnium oxide 10 years ago, the potential distribution at the nanoscale has only been modeled, but not directly measured.|
|The team employed a technique known as high-energy X-ray photoemission spectroscopy. The specialized methodology developed at MIPT relies on the so-called standing-wave mode of the powerful monochromatic X-ray beam, which requires a synchrotron light source to produce. The machine used in the study is located in Hamburg, Germany. It was used to perform measurements on the hafnium oxide-based memory cell prototypes manufactured at MIPT.|
|"If used for the industrial production of nonvolatile memory cells, the ferroelectric capacitors developed in our lab could endure 10 billion rewrite cycles, which is 100,000 times more than state-of-the-art flash drives can survive," said study co-author Andrei Zenkevich, who heads the Laboratory of Functional Materials and Devices for Nanoelectronics at MIPT.|
|A further advantage of ferroelectric memory devices is that external radiation has absolutely no effect on them, unlike their semiconductor-based analogues. This means that the flash-like memory of the future could even weather cosmic ray exposure and operate in outer space.|
|Source: Moscow Institute of Physics and Technology|
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