Controllable Formation of Nanofilaments in Resistive Memories via Tip‐Enhanced Electric Fields

Abstract

Resistive random access memory (ReRAM) has a great potential to be the next-generation non-volatile memory device. However, the random nucleation and growth of conductive fi laments (CFs) in ReRAM causes the low reliability in switching behaviors, leading to diffi culties in its practical application. This study demonstrates that manipulating electric fi elds in ReRAM via a structured electrode can provide the controllable formation of CFs. Ag pyramids that have a high-quality tip prepared via the template-stripping method generate highly enhanced electric fi elds at the tip. Because the tip-enhanced electric fi elds can facilitate the ionization of Ag atoms and their migration along the electric fi elds, the nucleation and growth of CFs occurs predominantly at the tip. The CFs in ReRAM are directly observed using electron microscopy and it is confi rmed that the CFs are formed only at the tip. The resulting ReRAM exhibits low and reliable SET/RESET voltages (0.48 V ± 0.02 V and 0.15 V ± 0.06 V, respectively). Moreover, its endurance and retention time are highly improved, compared to those devices that are based on conventional geometry. Thus, this approach can encourage creating high-performance ReRAM.

Photocatalytic Reduction of Graphene Oxide–TiO2 Nanocomposites for Improving Resistive‐Switching Memory Behaviors

“…Conventional methods are not completely compatible with current flexible electronic technology because some toxic reductants, such as hydrazine, are used for chemical reduction methods and high temperatures are required for thermal reduction . Furthermore, these methods are usually nonlocal, and the RGO‐domains are modified homogeneously throughout the entire GO film, which is undesirable for tuning RS behaviors …”

Resistive Switching Performance Improvement via Modulating Nanoscale Conductive Filament, Involving the Application of Two‐Dimensional Layered Materials

“…Previously, an AFM‐tip electrode is proved to have an effect of enhancing the electric field and strongly improves resistive parameters thanks to its tip structure accompanied with ultra‐small contact areas . Similarly, an Ag pyramidal electrode is designed and fabricated via an anisotropic etching method in Ag/Al 2 O 3 /Pt devices ( Figure ) . Compared to nanocrystal structures, pyramidal electrodes are much more efficient in concentrating electric field within an ultra‐confined region as well as leading to the ionization of Ag atoms (like a lightning rod).…”

“…Compared to nanocrystal structures, pyramidal electrodes are much more efficient in concentrating electric field within an ultra‐confined region as well as leading to the ionization of Ag atoms (like a lightning rod). Therefore, RS will mainly occur at the tip and metallic CF is more likely to grow with smaller diameter and can be fractured easily with less CF residue, which contributes to stable switching characteristic, low SET/RESET voltage and forming‐free behavior …”

“…The thickness of each layer is dimensioned in the image. Reproduced with permission . Copyright 2016, Wiley–VCH.…”

Unconventional Inorganic‐Based Memristive Devices for Advanced Intelligent Systems

“…After deposition of the top electrode (Au) and initial electric breakdown, a vertical nanogap with an RS property was generated, presenting a high HRS/LRS resistance ratio (>10 7 ), sub‐10 ns switching speed, and multistate storage ability, as shown in Figure f,g. Shin et al adopted a pyramid‐shaped Ag array as an electrode of the RS memory (Pt/Al 2 O 3 /Ag), achieving low set voltage of 0.48 V ± 0.02 V and reset voltage of 0.15 V ± 0.06 V with minimized deviations. Kim et al also reported an RS memory (TiN/TiO 2 /Cu cone/TiN) embedding a cone‐structured Cu cation source, showing improved RS properties compared to the conventional device with a planar bottom electrode.…”