Russian scientists have received the material based on hafnium oxide for the memory of new type

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Российские учёные получили материал на основе оксида гафния для памяти нового типа

Researchers from Moscow Institute of physics and technology (MIPT) was first grown ultrathin (2.5 nm) ferroelectric films on the basis of hafnium oxide, which can be the basis for elements of non-volatile memory of a new type.

We are talking about storage devices on the so-called ferroelectric tunnel junctions. The ferroelectric — substance is able to “remember” the direction of the applied external electric field by the residual polarization charges.

Российские учёные получили материал на основе оксида гафния для памяти нового типа

MIPT

Based on thin-film ferroelectrics has long made the device non-volatile memory, however, the possibility of miniaturization is extremely limited. About ten years ago, after have been demonstrated ferroelectric properties in ultrathin single-crystal films of perovskites, proposed an alternative concept of memory devices based on the use of a tunnel effect.

Ferroelectrics are insulators and do not conduct electricity. However, for very small thicknesses of the ferroelectric layer, the electrons with a certain probability still can “slip” through it due to the tunneling effect, has a quantum nature. The probability of tunneling depends on the size and shape of the potential barrier (the energy characteristics of the structure), and “slipped out” the electrons form a tunneling current.

The movement of electrons in this case resembles the steeplechase, and the magnitude of the obstacles is determined by the direction of the polarization vector, which changes the shape of the potential barrier (see figure above). Thus, recording of information is conducted by applying voltage to electrodes adjacent to the ferroelectric ultra-slim, and read by measuring the tunneling current.

Theoretically, such a memory can have very high densities, speeds of record and reading, and low power consumption. But there is a problem. Still all manufactured prototypes of devices based on traditional ferroelectrics were incompatible with silicon technology. Now Russian scientists in collaboration with U.S. and Swiss colleagues for the first time experimentally demonstrated that the fused polycrystalline films of oxides of hafnium and zirconium with a thickness of only 2.5 nm retain their ferroelectric properties.

Российские учёные получили материал на основе оксида гафния для памяти нового типа

The cross section of the fabricated structure / MIPT

The hafnium oxide is already used in the production of modern silicon logic circuits, and a few years ago in one of its modifications were detected ferroelectric properties. The merit of scientists from MIPT is that they managed to grow a thin tunnel-transparent film of this substance on a silicon substrate, while retaining its ferroelectric properties“, — stated in the message.

Thus, in the future on silicon can be created by new devices non-volatile memory using ferroelectric polycrystalline layers of hafnium oxide.

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