TiOx-based self-rectifying memory device for crossbar WORM memory array applications

Resistive switching with a self-rectifying feature is one of the most effective solutions to overcome the crosstalk issue in a crossbar array. In this paper, a memory device based on Pt/TiO_(x)/W structure with self-rectifying property is demonstrated for write-once-read-many-times(WORM) memory application. After programming, the devices exhibit excellent uniformity and keep in the low resistance state(LRS) permanently with a rectification ratio as high as 10^(4) at ±1 V. The self-rectifying resistive switching behavior can be attributed to the Ohmic contact at TiO_(x)/W interface and the Schottky contact at Pt/TiO_(x) interface. The results in this paper demonstrate the potential application of TiO_(x)-based WORM memory device in crossbar arrays.

Simultaneous resistance switching and rectifying effects in a single hybrid perovskite

Halide perovskites with naturally coupled electron-ion dynamics hold greatpotential for nonvolatile memory applications. Self-rectifying memristors arepromising as they can avoid sneak currents and simplify device configuration.Here we report a self-rectifying memristor firstly achieved in a single perovskite(NH CINH_(3))_(3)PbI_(5) (abbreviated as (IFA)_(3)PbI_(5)), which is sandwiched byAg and ITO electrodes as the simplest cell in a crossbar array device configuration.The iodide ions of (IFA)_(3)PbI_(5) can be easily activated, of which the migrationin the bulk contributes to the resistance hysteresis and the reaction withAg at the interface contributes to the spontaneous formation of AgI. The perfectcombination of n-type AgI and p-type (IFA)_(3)PbI_(5) gives rise to the rectificationfunction like a p–n diode. Such a self-rectifying memristor exhibits therecord-low set power consumption and voltage. This work emphasizes that themultifunction of ions in perovskites can simplify the fabrication procedure,decrease the programming power, and increase the integration density offuture memory devices.

Design and initial test results of a space-bound flux pump to energize the Heki mission's superconducting magnet

Despite repeated proposals to uillize superconducting magnets in space since at least the 1970s,examples of their use remain scant.One of the technical challenges is to maintai n sui table cryogenic temperatures on a spacecraft.This challenge can be alleviated by the use of flux pumps to reduce the required cryogenic cooling power needed to energize the superconducting magnet.This paper describes the design and initial test results of the flux pump to fulfll the requirements of the Haki mission that will operate a high-temperature supercon-ducting magnet on an extemal platorm of the Intemational Space Station.A transfomer based,self-recti fier architecture was chosen for the flux pump.An effecive circuit model used to deign its electromagnetc properties and fini teelement modelling used in its mechanical and thermal design.Liquid nitrogen tests were used to demonstrate that the electrical performance of the flux pump meets requirements.Higher-fidelity tests using flight-like copies of the hardware and software were undertaken and validated the thermal modelling.These tests also featured the continuous operation of the flux pump in a conduction-cooled setting for over 100 h,relecting an inherent reliability of this technology.Whilst further testing and flight qualification remains to be completed,we anticipate an on-orbit demonstration of this flux pump technology in April 2025.Such a demonstration will signal a maturing of this emergi ng superconducting technology for both in-space and terrestrial applications.

Progress in rectifying-based RRAM passive crossbar array

Resistive random access memory(RRAM) with crossbar structure is receiving widespread attentions due to its simple structure,high density,and feasibility of three-dimensional(3D) stack.It is an extremely promising solution for high density storage.However,a major issue of crosstalk restricts its development and application.In this paper,we will first introduce the integration methods of RRAM device and the existing crosstalk phenomenon in passive crossbar array,and then focus on the 1D1R(one diode and one resistor) structure and self-rectifying 1R(one resistor) structure which can restrain crosstalk and avoid misreading for the passive crossbar array.The test methods of crossbar array are also presented to evaluate the performances of passive crossbar array to achieve its commercial application in comparison with the active array consisting of one transistor and one RRAM cell(1T1R) structure.Finally,the future research direction of rectifying-based RRAM passive crossbar array is discussed.

Lithium incorporation enhanced resistive switching behaviors in lithium lanthanum titanium oxide-based heterostructure

Resistive switching devices with a high self-rectifying ratio are important for achieving the crossbar memristor array that overcomes the sneak current issue.Herein,we demonstrate a single amorphous lithium lanthanum titanium oxide(LLTO)layer based Pt/LLTO/Pt device possessing a self-rectifying ratio higher than 1 × 10^(4) that is comparable to the reported devices with complicated multi-layer stacking structures.Moreover,the device shows forming-free and highly uniform bipolar resistive switching(BRS)characteristic that facilitates the potential applications.The trap-controlled and trap-free space charge limited conductions are demonstrated to dominate the high and low resistance states of the device,respectively.The fast migration of lithium ions under external voltage accelerates the electron injection across the Pt/LLTO interface and also the space charge accumulation in the LLTO layer,and as a result,the high performance of the Pt/LLTO/Pt device was achieved.As demonstrated Pt/LLTO/Pt device sheds a light on the potential applications of the lithium ionic conductors in self-rectifying resistive switching devices.

Artificial synaptic and self-rectifying properties of crystalline(Na_(1-x)K_(x))NbO_(3)thin films grown on Sr_(2)Nb_(3)O_(10)nanosheet seed layers

Crystalline(Na_(1-x)K_(x))NbO_(3)(NKN)thin films were deposited on Sr_(2)Nb_(3)O_(10)/TiN/Si(S-TS)substrates at 370°C.Sr_(2)Nb_(3)O_(10)(SNO)nanosheets served as a template for the formation of crystalline NKN films at low temperatures.When the NKN film was deposited on one SNO monolayer,the NKN memristor exhibited normal bipolar switching characteristics,which could be attributed to the formation and destruction of oxygen vacancy filaments.Moreover,the NKN memristor with one SNO monolayer exhibited artificial synaptic properties.However,the NKN memristor deposited on two SNO monolayers exhibited self-rectifying bipolar switching properties,with the two SNO monolayers acting as tunneling barriers in the memristor.The conduction mechanism of the NKN memristor with two SNO monolayers in the highresistance state is attributed to Schottky emission,direct tunneling,and Fowler–Nordheim(FN)tunneling.The current conduction in this memristor in the low-resistance state was governed by direct tunneling and FN tunneling.Additionally,the NKN memristor with two SNO monolayers exhibited large ON/OFF and rectification ratios and artificial synaptic properties.Therefore,an NKN memristor with two SNO monolayers can be used for fabricating artificial synaptic devices with a cross-point array structure.

High-performance self-rectifying memristor array based on Pt/HfO_(2)/Ta_(2)O_(5−x)/Ti structure for flexible electronics

Self-rectifying memristor(SRM)arrays hold tremendous potential in high-density data storage and energy efficient neuromorphic computing.However,SRM arrays are mostly developed on rigid substrates and lack mechanical flexibility,limiting their applications in intelligent electronic skin,wearable technologies,etc.Here,we present a high performance SRM array based on Pt/HfO_(2)/Ta_(2)O_(5−x)/Ti heterojunctions,which can be fabricated on a flexible polyimides(PI)substrate and demonstrates exceptional memristive performance under bending conditions(bending radius(R)=1 cm,rectifying ratio>10^(4),retention time>10^(4) s and endurance>105 cycles).We demonstrate a 16×16 flexible memristor array offering noise filtering and data storage capabilities,which can be used to accurately process and store the signals transmitted by a pressure sensor array.This research represents an important advancement towards the realization of next-generation high-performance flexible electronics.