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.

Nanoscale Doping and Its Impact on the Ferroelectric and Piezoelectric Properties of HfZrO.

Ferroelectric hafnium oxide thin films-the most promising materials in microelectronics' non-volatile memory-exhibit both unconventional ferroelectricity and unconventional piezoelectricity. Their exact origin remains controversial, and the relationship between ferroelectric and piezoelectric properties remains unclear. We introduce a new method to investigate this issue, which consists in a local controlled modification of the ferroelectric and piezoelectric properties within a single HfZrO capacitor device through local doping and a further comparative nanoscopic analysis of the modified regions.

Bone conducted responses in the neonatal rat auditory cortex.

Rats are born deaf and start hearing at the end of the second postnatal week, when the ear canals open and low-intensity sounds start to evoke responses in the auditory cortex. Here, using μECoG electrode arrays and intracortical silicon probe recordings, we found that bone-conducted (BC) sounds evoked biphasic responses in the auditory cortex starting from postnatal day (P) 8. The initial phase of these responses, generated by thalamocortical input, was followed by intracortical propagation within supragranular layers.

SPP waveguide based on the Goos-Hänchen effect.

We propose and realize a single-mode surface plasmon polariton (SPP) waveguide formed by two parallel grooves on the surface of a high-quality silver film. In the waveguide, the SPP wave undergoes the Goos-Hänchen shift of up to 0.77⋅ at each successive reflection, with the electric field of the SPP wave outside the metal, which significantly reduces the metal loss of the guided SPP wave.

Defects in ferroelectric HfO.

The discovery of ferroelectricity in polycrystalline thin films of doped HfO2 has reignited the expectations of developing competitive ferroelectric non-volatile memory devices. To date, it is widely accepted that the performance of HfO2-based ferroelectric devices during their life cycle is critically dependent on the presence of point defects as well as structural phase polymorphism, which mainly originates from defects either. The purpose of this review article is to overview the impact of defects in ferroelectric HfO2 on its functional properties and the resulting performance of memory devices.

Band Excitation Piezoresponse Force Microscopy Adapted for Weak Ferroelectrics: On-the-Fly Tuning of the Central Band Frequency.

New interest in microscopic studies of ferroelectric materials with low piezoelectric coefficient, $d_{33}^\ast$, has emerged after the discovery of ferroelectric properties in HfO2 thin films, which are the main candidate for the next generation of nonvolatile ferroelectric memory. The study of the microscopic structure of ferroelectric HfO2 capacitors is crucial to get insights into the device behavior and performance. However, a small $d_{33}^\ast$ of ferroelectric HfO2 films leads to a low piezoresponse, especially in band excitation piezoresponse force microscopy (BE-PFM).

Nanoscale Tailoring of Ferroelectricity in a Thin Dielectric Film.

New opportunities in the development and commercialization of novel photonic and electronic devices can be opened following the development of technology-compatible arbitrary-shaped ferroelectrics encapsulated in a passive environment. Here, we report and experimentally demonstrate nanoscale tailoring of ferroelectricity by an arbitrary pattern within the nonferroelectric thin film. For inducing the ferroelectric nanoregions in the nonferroelectric surrounding, we developed a technology-compatible approach of local doping of a thin (10 nm) HfO film by Ga ions right in the thin-film capacitor device focused ion beam implantation.

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.

Crossbar Nanoscale HfO2-Based Electronic Synapses.

Crossbar resistive switching devices down to 40 × 40 nm(2) in size comprising 3-nm-thick HfO2 layers are forming-free and exhibit up to 10(5) switching cycles. Four-nanometer-thick devices display the ability of gradual switching in both directions, thus emulating long-term potentiation/depression properties akin to biological synapses. Both forming-free and gradual switching properties are modeled in terms of oxygen vacancy generation in an ultrathin HfO2 layer.

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.