A scheme for enabling the ultimate speed of threshold switching in phase change memory devices

Nishant Saxena,Rajamani Raghunathan,Anbarasu Manivannan

doi:10.1038/s41598-021-85690-9

Nishant Saxena, Rajamani Raghunathan + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-85690-9

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Abstract

Phase change materials exhibit threshold switching (TS) that establishes electrical conduction through amorphous material followed by Joule heating leading to its crystallization (set). However, achieving picosecond TS is one of the key challenges for realizing non-volatile memory operations closer to the speed of computing. Here, we present a trajectory map for enabling picosecond TS on the basis of exhaustive experimental results of voltage-dependent transient characteristics of Ge2Sb2Te5 phase-change memory (PCM) devices. We demonstrate strikingly faster switching, revealing an extraordinarily low delay time of less than 50 ps for an over-voltage equal to twice the threshold voltage. Moreover, a constant device current during the delay time validates the electronic nature of TS. This trajectory map will be useful for designing PCM device with SRAM-like speed.

Highlights

Phase change materials exhibit threshold switching (TS) that establishes electrical conduction through amorphous material followed by Joule heating leading to its crystallization
The threshold switching (TS) takes place above a critical voltage known as the threshold voltage (VT), characteristic of the active material, during which rapid breakdown of electrical resistance from amorphous-off (a-off) to a conducting (a-on) state is evidenced by a steep rise in the device current (Id)[6]
The steadystate VT of the device is identified by the application of voltage pulse by gradually increasing the amplitude and observing the voltage at which the breakdown of electrical resistance takes place

Summary

Introduction

Phase change materials exhibit threshold switching (TS) that establishes electrical conduction through amorphous material followed by Joule heating leading to its crystallization (set). The threshold switching (TS) takes place above a critical voltage known as the threshold voltage (VT), characteristic of the active material, during which rapid breakdown of electrical resistance from amorphous-off (a-off) to a conducting (a-on) state is evidenced by a steep rise in the device current (Id)[6].

Results

Conclusion