Exploring ultrafast threshold switching in In3SbTe2 phase change memory devices

Abstract

Phase change memory (PCM) offers remarkable features such as high-speed and non-volatility for universal memory. Yet, simultaneously achieving better thermal stability and fast switching remains a key challenge. Thus, exploring novel materials with improved characteristics is of utmost importance. We report here, a unique property-portfolio of high thermal stability and picosecond threshold switching characteristics in In3SbTe2 (IST) PCM devices. Our experimental findings reveal an improved thermal stability of amorphous IST compared to most other phase change materials. Furthermore, voltage dependent threshold switching and current-voltage characteristics corroborate an extremely fast, yet low electric field threshold switching operation within an exceptionally small delay time of less than 50 picoseconds. The combination of low electric field and high speed switching with improved thermal stability of IST makes the material attractive for next-generation high-speed, non-volatile memory applications.

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

“…Though the electronic and thermal theories have contrasting philosophies, both agree that the voltage dependence of time delay is exponential. However, for the reasons discussed above, we believe that the thermal effects have a minimal role in the onset of threshold switching, at least in the extremely fast timescales of sub-50 ps as observed in GST as well as In 3 SbTe 2 devices 41 . We also calculated the minimum time taken ( t min ) by a charge carrier under the ballistic regime to transit through the chalcogenide film of thickness L = 53 nm and mobility µ = 1 cm 2 /(V s) using the relation t min = L/(E × µ) where E is the electric field.…”

High‐Stability and Low‐Noise Multilevel Switching in In3SbTe2 Material for Phase Change Photonic Memory Applications

“…[20] Although multilevel switching in IST was extensively explored nearly twenty years ago, [21] most of the studies were performed on compositions that exhibit multiple crystalline phases that hamper the reliability and reproducibility of multilevel operations. Nevertheless, in this work, we have successfully demonstrated eight distinct reflectivity levels between the set and reset states on thin IST film, which shows that a single-phase stoichiometric IST phase is stable even up to 325 C. [20] The subsequent optical states maintain a uniform reflectivity contrast, and the high stability of IST has demonstrated fewer variations in the measured reflectivity during the repeatable switching cycles. Furthermore, the local structure at different optical levels has been studied using confocal Raman spectroscopy to elucidate the structural evolution of multilevel switching.…”

Designing Crystallization to Tune the Performance of Phase-Change Memory: Rules of Hierarchical Melt and Coordinate Bond

“…Generally, a criterion is used by choosing metals with high cohesive energy or high melting point. 9 While some elements, such as Al 27 , Ga 28 , In 29 , and Sn 30 , present low cohesive energy or low melting point, they, to our surprise, can stabilize the amorphous well. This gives us a hint that it probably exists a deeper reason.…”