Projected phase-change memory devices

Abstract

Nanoscale memory devices, whose resistance depends on the history of the electric signals applied, could become critical building blocks in new computing paradigms, such as brain-inspired computing and memcomputing. However, there are key challenges to overcome, such as the high programming power required, noise and resistance drift. Here, to address these, we present the concept of a projected memory device, whose distinguishing feature is that the physical mechanism of resistance storage is decoupled from the information-retrieval process. We designed and fabricated projected memory devices based on the phase-change storage mechanism and convincingly demonstrate the concept through detailed experimentation, supported by extensive modelling and finite-element simulations. The projected memory devices exhibit remarkably low drift and excellent noise performance. We also demonstrate active control and customization of the programming characteristics of the device that reliably realize a multitude of resistance states.

Redefining the Speed Limit of Phase Change Memory Revealed by Time-resolved Steep Threshold-Switching Dynamics of AgInSbTe Devices

“…Moreover, switching from amorphous off to on state was achieved within a short time as small as 250 ps. This is approximately one order of magnitude faster than the threshold-switching speeds previously achieved in PCM devices171831 and particularly GeTe-based PC materials530.…”

“…This unique switching property-portfolio of AIST devices is ideally suited for PC-RAM and also towards universal memory. There is further evidence in the form of the most successful optical memory products such as re-writable digital versatile discs (DVDs) and Blu-Ray discs that use AIST as the key material, which belongs to the second family of PC materials1 owing to its remarkable properties such as high-speed crystal growth velocities21313334 and easily reversible nature with better structural stability12935. Furthermore, recent work36 on the relation between band gap and resistance drift in amorphous AIST material demonstrated a strikingly lower drift of the apparent activation energy compared with GeTe, GeSbTe materials.…”

Unconventional Inorganic‐Based Memristive Devices for Advanced Intelligent Systems

“…Copyright 2018, John Wiley & Sons. i–k) Reproduced with permission . Copyright 2015, the authors, published by Springer Nature under the terms of the CC‐BY Creative Commons Attribution 4.0 International License.…”

“…The encapsulated GeTe with extremely small volume showed a lowered melting point compared to its bulk material, which has beneficial effects of reducing the programming current of GeTe phase switching. Koelmans et al presented a unique PCM cell design, called projected PCM, composed of parallel domains of noninsulating projection and phase‐switching segment in a single cell, as shown in Figure i,j. The properties of high disorder and defect density of the phase switching material are known to result in a high noise level and resistance drift during the PCM operation.…”

Recent Progress in Synaptic Devices Based on 2D Materials

“…Various synaptic devices based on resistive switching, driven by different physical working mechanisms such as active metallic filament, charge trapping/detrapping effect, ions/vacancies migration, phase change behaviors, ferroelectric polarization, and spin‐transfer torque‐based synapses, have been demonstrated for emerging memory and neuromorphic computing. Many scientists are actively working to resolve various issues in those synaptic devices: high energy consumption, low switching speed, poor reliability, or the lack of high device density for integration.…”