Giant Electromechanical Effect in Piezoelectric Nanomembranes Based on HfZrO.

Since ultrathin ferroelectric HfO films can be conformally grown by atomic layer deposition even on complex three-dimensional structures, new horizons in the development of next-generation piezoelectric devices are opened. However, hafnium oxide has a significant drawback for piezoelectric applications: its piezoelectric coefficients are much smaller than those of classical materials currently used in piezoelectric devices. Therefore, new approaches to the development of high-performance piezoelectric devices based on exploiting the unique properties of HfO are of paramount importance.

Effect of Domain Structure and Dielectric Interlayer on Switching Speed of Ferroelectric HfZrO Film.

The nanosecond speed of information writing and reading is recognized as one of the main advantages of next-generation non-volatile ferroelectric memory based on hafnium oxide thin films. However, the kinetics of polarization switching in this material have a complex nature, and despite the high speed of internal switching, the real speed can deteriorate significantly due to various external reasons. In this work, we reveal that the domain structure and the dielectric layer formed at the electrode interface contribute significantly to the polarization switching speed of 10 nm thick HfZrO (HZO) film.

Wake-Up Free Ultrathin Ferroelectric HfZrO Films.

The development of the new generation of non-volatile high-density ferroelectric memory requires the utilization of ultrathin ferroelectric films. The most promising candidates are polycrystalline-doped HfO films because of their perfect compatibility with silicon technology and excellent ferroelectric properties. However, the remanent polarization of HfO films is known to degrade when their thickness is reduced to a few nanometers.

Magnetoelectric Coupling at the Ni/HfZrO Interface.

Composite multiferroics containing ferroelectric and ferromagnetic components often have much larger magnetoelectric coupling compared to their single-phase counterparts. Doped or alloyed HfO-based ferroelectrics may serve as a promising component in composite multiferroic structures potentially feasible for technological applications. Recently, a strong charge-mediated magnetoelectric coupling at the Ni/HfO interface has been predicted using density functional theory calculations.

Controlling Charge Transfer from Quantum Dots to Polyelectrolyte Layers Extends Prospective Applications of Magneto-Optical Microcapsules.

The layer-by-layer (LbL) deposition approach allows combined incorporation of fluorescent, magnetic, and plasmonic nanoparticles into the shell of polyelectrolyte microcapsules to obtain stimulus-responsive systems whose imaging and drug release functions can be triggered by external stimuli. The combined use of fluorescent quantum dots (QDs) and magnetic nanoparticles (MNPs) yields magnetic-field-driven imaging tools that can be tracked and imaged even deep in tissue when the appropriate type of QDs and wavelength of their excitation are used. QDs are excellent photonic labels for microcapsule encoding due to their close-to-unity photoluminescence (PL) quantum yields, narrow PL emission bands, and tremendous one- and two-photon extinction coefficients.

On-Chip TaO -Based Non-volatile Resistive Memory for Neurointerfaces.

The development of highly integrated electrophysiological devices working in direct contact with living neuron tissue opens new exciting prospects in the fields of neurophysiology and medicine, but imposes tight requirements on the power dissipated by electronics. preprocessing of neuronal signals can substantially decrease the power dissipated by external data interfaces, and the addition of embedded non-volatile memory would significantly improve the performance of a co-processor in real-time processing of the incoming information stream from the neuron tissue. Here, we evaluate the parameters of TaO -based resistive switching (RS) memory devices produced by magnetron sputtering technique and integrated with the 180-nm CMOS field-effect transistors as possible candidates for on-chip memory in the hybrid neurointerface under development.

Memristor with a ferroelectric HfO layer: in which case it is a ferroelectric tunnel junction.

New interest in the implementation of ferroelectric tunnel junctions has emerged following the discovery of ferroelectric properties in HfO films, which are fully compatible with silicon microelectronics technology. The coercive electric field to switch polarization direction in ferroelectric HfO is relatively high compared to classical perovskite materials, and thus it can cause the migration of non-ferroelectric charges in HfO, namely charged oxygen vacancies. The charge redistribution would cause the change of the tunnel barrier shape and following change of the electroresistance effect.

Polarization-dependent electric potential distribution across nanoscale ferroelectric HfZrO in functional memory capacitors.

The emergence of ferroelectricity in nanometer-thick films of doped hafnium oxide (HfO) makes this material a promising candidate for use in Si-compatible non-volatile memory devices. The switchable polarization of ferroelectric HfO controls functional properties of these devices through the electric potential distribution across the capacitor. The experimental characterization of the local electric potential at the nanoscale has not so far been realized in practice.

Ferroelectric Second-Order Memristor.

While the conductance of a first-order memristor is defined entirely by the external stimuli, in the second-order memristor it is governed by the both the external stimuli and its instant internal state. As a result, the dynamics of such devices allows to naturally emulate the temporal behavior of biological synapses, which encodes the spike timing information in synaptic weights. Here, we demonstrate a new type of second-order memristor functionality in the ferroelectric HfO-based tunnel junction on silicon.

Ferroelectricity in HfZrO Thin Films: A Microscopic Study of the Polarization Switching Phenomenon and Field-Induced Phase Transformations.

Because of their full compatibility with the modern Si-based technology, the HfO-based ferroelectric films have recently emerged as viable candidates for application in nonvolatile memory devices. However, despite significant efforts, the mechanism of the polarization switching in this material is still under debate. In this work, we elucidate the microscopic nature of the polarization switching process in functional HfZrO-based ferroelectric capacitors during its operation.

Effect of Polarization Reversal in Ferroelectric TiN/HfZrO/TiN Devices on Electronic Conditions at Interfaces Studied in Operando by Hard X-ray Photoemission Spectroscopy.

Because of their compatibility with modern Si-based technology, HfO-based ferroelectric films have recently attracted attention as strong candidates for applications in memory devices, in particular, ferroelectric field-effect transistors or ferroelectric tunnel junctions. A key property defining the functionality of these devices is the polarization dependent change of the electronic band alignment at the metal/ferroelectric interface. Here, we report on the effect of polarization reversal in functional ferroelectric TiN/HfZrO/TiN capacitors on the potential distribution across the stack and the electronic band line-up at the interfaces studied in operando by hard X-ray photoemission spectroscopy.

Ultrathin Hf0.5Zr0.5O2 Ferroelectric Films on Si.

Because of their immense scalability and manufacturability potential, the HfO2-based ferroelectric films attract significant attention as strong candidates for application in ferroelectric memories and related electronic devices. Here, we report the ferroelectric behavior of ultrathin Hf0.5Zr0.

[Molecular and epidemiologic characteristics of HIV-infection outbreak in the Irkutsk region].

The genetic analysis of the variants of human immunodeficiency virus of type 1 (HIV-I) circulating among drug addicts in the Irkutsk region was carried out. The results of serological tests and comparative evaluation of electrophoretic mobility of heteroduplexes (HMA) revealed that all 74 samples under study belonged to subtype A. Genetic differences between these viruses did not exceed 2%.