Fast phase transitions induced by picosecond electrical pulses on phase change memory cells

Wang, W. J.; Shi, Lu; Zhao, Ruixue; Lim, Kian Guan; Lee, H. K.; Chong, Tow Chong; Wu, Yihong

doi:10.1063/1.2963196

Cited by 157 publications

(100 citation statements)

References 17 publications

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“…This required annealing of the film is discussed in [14]. In our simulation, a 15 V pulse was applied for 2 ns to the waveguided crystal GST having 2770 S/m conductivity [13], and here the result was a current density of 6.7 A/m 2 induced in GST.…”

Section: Electrically Induced Phase Changementioning

confidence: 99%

Simulations of Silicon-on-Insulator Channel-Waveguide Electrooptical 2 × 2 Switches and 1 × 1 Modulators Using a ${\bf Ge_2}{\bf Sb_2}{\bf Te_5}$ Self-Holding Layer

Liang

Soref

et al. 2015

J. Lightwave Technol.

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This paper reports theoretical designs and simulations of electrooptical 2 × 2 switches and 1 × 1 loss modulators based upon GST-embedded SOI channel waveguides. It is assumed that the amorphous and crystalline phases of GST can be triggered electrically by Joule heating current applied to a 10-nm GST film sandwiched between doped-Si waveguide strips. TE o and TM o mode effective indices are calculated over 1.3 to 2.1-μm wavelength range. For 2 × 2 Mach-Zehnder and directional coupler switches, low insertion loss, low crosstalk, and short device lengths are predicted for 2.1 μm, although a decreased performance is projected for 1.55 μm. For 1.3-2.1 μm, the 1 × 1 EO waveguide has application as a variable optical attenuator and as a digital modulator, albeit with ࣚ100-ns state-transition time. Because the active material has two "stable" phases, the device holds itself in either state, and voltage needs to be applied only during transition.

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Section: Electrically Induced Phase Changementioning

confidence: 99%

Simulations of Silicon-on-Insulator Channel-Waveguide Electrooptical 2 × 2 Switches and 1 × 1 Modulators Using a ${\bf Ge_2}{\bf Sb_2}{\bf Te_5}$ Self-Holding Layer

Liang

Soref

et al. 2015

J. Lightwave Technol.

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“…Generally, a fast crystal-to-glass transition is realized through applying a high input energy, which promotes rapid structural disordering in GST (15)(16)(17). As predicted, the GST cell exhibits faster switching from the crystalline to glassy states for both NOR and NOT operations as the amplitudes of the LO/HI electrical pulses are increased from 1.55/1.70 to 4.6/ 5.0 V (Fig.…”

Section: Significancementioning

confidence: 69%

Ultrafast phase-change logic device driven by melting processes

Loke

Skelton

Wang

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The ultrahigh demand for faster computers is currently tackled by traditional methods such as size scaling (for increasing the number of devices), but this is rapidly becoming almost impossible, due to physical and lithographic limitations. To boost the speed of computers without increasing the number of logic devices, one of the most feasible solutions is to increase the number of operations performed by a device, which is largely impossible to achieve using current silicon-based logic devices. Multiple operations in phase-change-based logic devices have been achieved using crystallization; however, they can achieve mostly speeds of several hundreds of nanoseconds. A difficulty also arises from the tradeoff between the speed of crystallization and long-term stability of the amorphous phase. We here instead control the process of melting through premelting disordering effects, while maintaining the superior advantage of phase-change-based logic devices over silicon-based logic devices. A melting speed of just 900 ps was achieved to perform multiple Boolean algebraic operations (e.g., NOR and NOT). Ab initio molecular-dynamics simulations and in situ electrical characterization revealed the origin (i.e., bond buckling of atoms) and kinetics (e.g., discontinuouslike behavior) of melting through premelting disordering, which were key to increasing the melting speeds. By a subtle investigation of the well-characterized phase-transition behavior, this simple method provides an elegant solution to boost significantly the speed of phase-change-based in-memory logic devices, thus paving the way for achieving computers that can perform computations approaching terahertz processing rates.computing | chalcogenides T he extremely high and ever-increasing demand for faster computers is currently addressed by traditional methods, such as miniaturization (to increase the number of devices), but this is rapidly becoming almost impossible, due to physical and lithographic constraints (1-4). The speed of computers is known to be determined almost solely by the performance of logic devices, i.e., their speed and number, which control most computations (or processes) in computers (5). Logic devices are mostly required to operate around 1 ns for achieving fast computations, and to transfer information between alternate devices, such as random-access memories, without delays (5). To increase the speed of computers without increasing the number of logic devices, one of the most feasible methods is to increase the number of operations performed by a device, which is largely unachievable using current silicon-based logic devices (6, 7).Multiple operations in a logic device are currently best achieved using devices comprised of phase-change nonvolatile memory materials-based on the reversible and multilevel switching of a phase-change material (PCM) between crystalline and glassy states having a contrast in physical properties, e.g., electrical resistivity (8, 9)-which can perform more than three times the number of operations than can s...

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“…The melt-quench process is quite fast. For example, switching to the amorphous state of Ge 2 Sb 2 Te 5 has been demonstrated with electrical pulses with durations as short as 400 ps [7]. Because a high current is required to melt the material, the RESET operation dominates the power consumption.…”

Section: Physics Of Pcmmentioning

confidence: 99%

Phase change memory

Lam

2011

Sci. China Inf. Sci.

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Phase change memory (PCM) is a non-volatile solid-state memory technology based on the large resistivity contrast between the amorphous and crystalline states in phase change materials. We present the physics behind this large resistivity contrast and describe how it is being exploited to create high density PCM. We address the challenges facing this technology, including the design of PCM cells, fabrication, device variability, thermal cross-talk and write disturb. We discuss the scalability, assess the performance, and examine the reliability of PCM including data retention, multi-bit storage and endurance.

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Fast phase transitions induced by picosecond electrical pulses on phase change memory cells

Cited by 157 publications

References 17 publications

Simulations of Silicon-on-Insulator Channel-Waveguide Electrooptical 2 × 2 Switches and 1 × 1 Modulators Using a ${\bf Ge_2}{\bf Sb_2}{\bf Te_5}$ Self-Holding Layer

Simulations of Silicon-on-Insulator Channel-Waveguide Electrooptical 2 × 2 Switches and 1 × 1 Modulators Using a ${\bf Ge_2}{\bf Sb_2}{\bf Te_5}$ Self-Holding Layer

Ultrafast phase-change logic device driven by melting processes

Phase change memory

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