Resistive random access memory (ReRAM) is a promising candidate for future nonvolatile memories. Resistive switching in a metal-insulator-metal structure is generally assumed to be caused by the formation/rupture of nanoscale conductive filaments (CFs) under an applied electric field. The critical issue of ReRAM for practical memory applications, however, is insufficient repeatability of the operating voltage and resistance ratio. Here, we present an innovative approach to reliably and reproducibly control the CF growth in unipolar NiO resistive memory by exploiting uniform formation of insulating SiOx nanostructures from the self-assembly of a Si-containing block copolymer. In this way, the standard deviation (SD) of set and reset voltages was markedly reduced by 76.9% and 59.4%, respectively. The SD of high resistance state also decreased significantly, from 6.3 × 10(7) Ω to 5.4 × 10(4) Ω. Moreover, we report direct observations of localized metallic Ni CF formation and their controllable growth using electron microscopy and discuss electrothermal simulation results based on the finite element method supporting our analysis results.

Memristor devices based on electrochemical metallization operate through electrochemical formation/dissolution of nanoscale metallic filaments, and they are considered a promising future nonvolatile memory because of their outstanding characteristics over conventional charge-based memories. However, nanoscale conductive paths or filaments precipitated from the redox process of metallic elements are randomly formed inside oxides resulting in unexpected and stochastic memristive switching parameters including the operating voltage and the resistance state. Here, we present the guided formation of conductive filaments in Ag nanocone/SiO nanomesh/Pt memristors fabricated by high-resolution nanotransfer printing. Consequently, the uniformity of the memristive switching behavior is significantly improved by the existence of electric field-concentrator arrays consisting of Ag nanocones embedded in SiO nanomesh structures. This selective and controlled filament growth was experimentally supported by analyzing simultaneously the surface morphology and current-mapping results using conductive atomic-force microscopy. Moreover, stable multi-level switching operations with four discrete conduction states were achieved by the nanopatterned memristor device demonstrating its potential in high-density nanoscale memory devices.

Crossbar-structured memory comprising 32 × 32 arrays with one selector-one resistor (1S-1R) components are initially fabricated on a rigid substrate. They are transferred without mechanical damage via an inorganic-based laser lift-off (ILLO) process as a result of laser-material interaction. Addressing tests of the transferred memory arrays are successfully performed to verify mitigation of cross-talk on a plastic substrate.

Flexible memory is the fundamental component for data processing, storage, and radio frequency communication in flexible electronic systems. Among several emerging memory technologies, phase-change random-access memory (PRAM) is one of the strongest candidate for next-generation nonvolatile memories due to its remarkable merits of large cycling endurance, high speed, and excellent scalability. Although there are a few approaches for flexible phase-change memory (PCM), high reset current is the biggest obstacle for the practical operation of flexible PCM devices. In this paper, we report a flexible PCM realized by incorporating nanoinsulators derived from a Si-containing block copolymer (BCP) to significantly lower the operating current of the flexible memory formed on plastic substrate. The reduction of thermal stress by BCP nanostructures enables the reliable operation of flexible PCM devices integrated with ultrathin flexible diodes during more than 100 switching cycles and 1000 bending cycles.

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Inorganic phase change memories (PCMs) have attracted substantial attention as a next‐generation storage node, due to their high‐level of performance, reliability, and scalability. To integrate the PCM on plastic substrates, the reset power should be minimized to avoid thermal degradation of polymers and adjacent cells. Additionally, flexible phase change random access memory remains unsolved due to the absence of the optimal transfer method and the selection device. Here, an Mo‐based interfacial physical lift‐off transfer method is introduced to realize a crossbar‐structured flexible PCM array, which employs a Schottky diode (SD) selection device and conductive filament PCM storage node. A 32 × 32 parallel array of 1 SD‐1 CFPCM, which utilizes a Ni filament as a nanoheater for low power phase transition, is physically exfoliated from the glass substrate at the face‐centered cubic/body‐centered cubic interface within the sacrificial Mo layer. First principles density functional theory calculations are utilized to understand the mechanism of the Mo‐based exfoliation phenomena and the observed metastable Mo phase. The flexible 1 SD‐1 CFPCM shows reliable operations (e.g., large resistance ratio of 17, excellent endurance over 100 cycles, and long retention over 104 s) with excellent flexibility. Furthermore, the random access operation is confirmed by addressing tests of characters “KAIST.”

Ge2Sb2Te5-based phase-change memories (PCMs), which undergo fast and reversible switching between amorphous and crystalline structural transformation, are being utilized for nonvolatile data storage. However, a critical obstacle is the high programming current of the PCM cell, resulting from the limited pattern size of the optical lithography-based heater. Here, we suggest a facile and scalable strategy of utilizing self-structured conductive filament (CF) nanoheaters for Joule heating of chalcogenide materials. This CF nanoheater can replace the lithographical-patterned conventional resistor-type heater. The sub-10 nm contact area between the CF and the phase-change material achieves significant reduction of the reset current. In particular, the PCM cell with a single Ni filament nanoheater can be operated at an ultralow writing current of 20 μA. Finally, phase-transition behaviors through filament-type nanoheaters were directly observed by using transmission electron microscopy.

We report the demonstration of low power phase change memory (PCM) by forming thin self-assembled SiO x nanostructures between Ge 2 Sb 2 Te 5 (GST) and a TiN heater layer utilizing a block copolymer (BCP) self-assembly technology. The reset current was decreased about threefold as fill factor, which is the occupying area fraction of self-assembled SiO x nanostructures on a TiN heater layer, increased to 75.3%. The electro-thermal simulation shows the better heat efficiency due to the nano-patterned insulating oxide.