Beyond von‐Neumann Computing with Nanoscale Phase‐Change Memory Devices

Abstract

Historically, the application of phase-change materials and devices has been limited to the provision of non-volatile memories. Recently, however, the potential has been demonstrated for using phase-change devices as the basis for new forms of brain-like computing, by exploiting their multilevel resistance capability to provide electronic mimics of biological synapses. Here, a different and previously under-explored property that is also intrinsic to phase-change materials and devices, namely accumulation, is exploited to demonstrate that nanometer-scale electronic phase-change devices can also provide a powerful form of arithmetic computing. Complicated arithmetic operations are carried out, including parallel factorization and fractional division, using simple nanoscale phase-change cells that process and store data simultaneously and at the same physical location, promising a most effi cient and effective means for implementing beyond von-Neumann computing. This same accumulation property can be used to provide a particularly simple form phase-change integrate-and-fi re "neuron", which, by combining both phase-change synapse and neuron electronic mimics, potentially opens up a route to the realization of all-phase-change neuromorphic processing.

How Supercooled Liquid Phase-Change Materials Crystallize: Snapshots after Femtosecond Optical Excitation

“…The resulting understanding of fs-induced crystallization might be particularly helpful for the application of PCMs as active optics [40][41][42] , which can be operated significantly faster after initiating the PCM accordingly. Similar effects have been motivated by the realization of neuromorphic computation using sub-threshold electrical pulses to initiate phase-change devices with pulses of 10 ns duration 43 . This initialization with a limited number of effectively shortens the remaining crystallization process, explaining what has been demonstrated using pre-pulses below the crystallization threshold on longer timescales 44 .…”

Crystal growth within a phase change memory cell

“…The experiment is repeated for ambient temperatures ranging from 353 to 543 K. The results are shown in Fig. 1b together with the fitted time evolution from equations (4) and (5). From the fits, v g 0 ðTÞ is obtained and shown in Fig.…”

“…In particular, phase change memory (PCM) has recently emerged as the most promising new nonvolatile solid-state memory technology [1][2][3] . Phase-change materials are also being investigated as building blocks of neuromorphic computing hardware [4][5][6] .…”

Mixed‐Mode Electro‐Optical Operation of Ge2Sb2Te5 Nanoscale Crossbar Devices

“…This property has been referred to as accumulation and occurs by means of optical as well as electrical pulses. [14][15][16] In this work therefore we investigate the phase transition of GST by simultaneously examining the optical and electrical responses of crossbar-type nanoscale devices exposed to cumulative optical and electrical excitations.…”