scholarly journals Recipe for ultrafast and persistent phase-change memory materials

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Keyuan Ding ◽  
Bin Chen ◽  
Yimin Chen ◽  
Junqiang Wang ◽  
Xiang Shen ◽  
...  
Keyword(s):  
Phase Change ◽  
High Performance ◽  
Phase Change Materials ◽  
Elevated Temperatures ◽  
Random Access ◽  
Supercooled Liquid ◽  
Atomic Diffusion ◽  
Working Mechanism ◽  
Ambient Temperatures ◽  
Crystallization Speed

Abstract The contradictory nature of increasing the crystallization speed while extending the amorphous stability for phase-change materials (PCMs) has long been the bottleneck in pursuing ultrafast yet persistent phase-change random-access memory. Scandium antimony telluride alloy (ScxSb2Te3) represents a feasible route to resolve this issue, as it allows a subnanosecond SET speed but years of reliable retention of the RESET state. To achieve the best device performances, the optimal composition and its underlying working mechanism need to be unraveled. Here, by tuning the doping dose of Sc, we demonstrate that Sc0.3Sb2Te3 has the fastest crystallization speed and fairly improved data nonvolatility. The simultaneous improvement in such ‘conflicting’ features stems from reconciling two dynamics factors. First, promoting heterogeneous nucleation at elevated temperatures requires a higher Sc dose to stabilize more precursors, which also helps suppress atomic diffusion near ambient temperatures to ensure a rather stable amorphous phase. Second, however, enlarging the kinetic contrast through a fragile-to-strong crossover in the supercooled liquid regime should require a moderate Sc content; otherwise, the atomic mobility for crystal growth at elevated temperatures will be considerably suppressed. Our work thus reveals the recipe by tailoring the crystallization kinetics to design superior PCMs for the development of high-performance phase-change working memory technology.

scholarly journals Metal - Insulator Transition Driven by Vacancy Ordering in GeSbTe Phase Change Materials

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Valeria Bragaglia ◽  
Fabrizio Arciprete ◽  
Wei Zhang ◽  
Antonio Massimiliano Mio ◽  
Eugenio Zallo ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Random Access ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Reversible Transformation ◽  
Vacancy Ordering

Abstract Phase Change Materials (PCMs) are unique compounds employed in non-volatile random access memory thanks to the rapid and reversible transformation between the amorphous and crystalline state that display large differences in electrical and optical properties. In addition to the amorphous-to-crystalline transition, experimental results on polycrystalline GeSbTe alloys (GST) films evidenced a Metal-Insulator Transition (MIT) attributed to disorder in the crystalline phase. Here we report on a fundamental advance in the fabrication of GST with out-of-plane stacking of ordered vacancy layers by means of three distinct methods: Molecular Beam Epitaxy, thermal annealing and application of femtosecond laser pulses. We assess the degree of vacancy ordering and explicitly correlate it with the MIT. We further tune the ordering in a controlled fashion attaining a large range of resistivity. Employing ordered GST might allow the realization of cells with larger programming windows.

Thermal Contact Resistance of Phase Change and Grease Type Polymeric Materials

2000 ◽  
Author(s):  
Ravi S. Prasher ◽  
Craig Simmons ◽  
Gary Solbrekken
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Phase Change ◽  
High Performance ◽  
Phase Change Materials ◽  
Thermal Contact ◽  
Polymeric Materials ◽  
Thermal Interface Material ◽  
Heat Spreader ◽  
Thermal Grease

Abstract Thermal interface material (TIM) between the die and the heat spreader or between the heat spreader and the heat sink in any electronic package plays a very important role in the thermal management of electronic cooling. Due to increased power and power density high-performance TIMs are sought every day. Phase change materials (PCM) seem to be very good alternative to traditionally used thermal greases because of various reasons. These phase change materials also have the advantage of being reworked easily without damaging the die. Typically these phase change materials are polymer based and are particle laden to enhance their thermal conductivity. The thermal conductivity of these materials is relatively well understood than their contact resistance. Current work focuses on explicitly measuring the contact resistance and the thermal conductivity of a particular phase change TIM and some silicon-based greases. Effect of various parameters, which can affect the contact resistance of theses TIMs and Greases, are also captured. The steady state measurements of the thermal conductivity and the contact resistance was done on an interface tester. In general the work on the contact resistance of fluid-like polymer based TIM, such as thermal grease or phase change polymer has been experimental in the past. A semi-analytical model, which captures the various parameters affecting the contact resistance of two class of materials; the phase change and the thermal grease is also developed in this paper. This model fits very well with the experimental data.

Magnetically tightened form-stable phase change materials with modular assembly and geometric conformality features

2021 ◽  
Author(s):  
Yongyu Lu ◽  
Dehai Yu ◽  
Haoxuan Dong ◽  
Jinran Lv ◽  
Lichen Wang ◽  
...  
Keyword(s):  
Phase Change ◽  
High Performance ◽  
Magnetic Particles ◽  
Phase Change Materials ◽  
Stable Phase ◽  
Free Standing ◽  
Modular Assembly ◽  
Significant Step ◽  
Dynamic Assembly ◽  
Surrounding Space

Abstract Recently, phase change materials (PCMs) have attracted significant attention due to their promising applications in many fields like solar energy and chip cooling. However, the present PCMs seriously suffer inevitable leakage and low thermal conduction. Magnetism can produce invisible field effects in the surrounding space. If there exist magnetic particles within this region, the effects will act on them emerging various fascinating phenomena. Inspired by this, we introduce hard magnetic particles (which can keep the effect after removing the magnetic field) to PCMs synthesizing an unprecedented magnetically tightened form-stable PCMs (MTPCMs), achieving multifunctions of leakage-proof, dynamic assembly and morphological reconfiguration, superior high thermal (increasing of 1400%~1600%) and electrical (>104 S/m) conductivity, and prominent compressive strength. Novel free-standing temperature control and high-performance thermal and electric conversion systems based on MTPCMs are furthermore developed. This work is a significant step toward exploiting a smart PCM for electronics and low-temperature energy storage.

High-performance composite phase change materials for energy conversion based on macroscopically three-dimensional structural materials

2019 ◽  
Vol 6 (2) ◽  
pp. 250-273 ◽  
Author(s):  
Jie Yang ◽  
Li-Sheng Tang ◽  
Lu Bai ◽  
Rui-Ying Bao ◽  
Zheng-Ying Liu ◽  
...  
Keyword(s):  
Phase Change ◽  
Energy Conversion ◽  
High Performance ◽  
Phase Change Materials ◽  
Three Dimensional ◽  
Structural Materials ◽  
Shape Stability ◽  
Efficient Energy ◽  
Composite Phase Change Materials ◽  
High Performance Composite

Macroscopically three-dimensional structural materials endow composite phase change materials with enhanced comprehensive performance, including excellent shape stability, high thermal conductivity and efficient energy conversion.

scholarly journals Numerical Analysis of the Energy Improvement of Plastering Mortars with Phase Change Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
A. Váz Sá ◽  
R. M. S. F. Almeida ◽  
H. Sousa ◽  
J. M. P. Q. Delgado
Keyword(s):  
Phase Change ◽  
Energy Demand ◽  
Phase Change Materials ◽  
Storage Capacity ◽  
Heat Storage ◽  
Indoor Temperature ◽  
Ambient Temperatures ◽  
Simulation Tools ◽  
Building Components ◽  
Cooling Energy Demand

Building components with incorporated phase change materials (PCMs) meant to increase heat storage capacity and enable stabilization of interior buildings surface temperatures, whereby influencing the thermal comfort sensation and the stabilization of the interior ambient temperatures. The potential of advanced simulation tools to evaluate and optimize the usage of PCM in the control of indoor temperature, allowing for an improvement in the comfort conditions and/or in the cooling energy demand, was explored. This paper presents a numerical and sensitivity analysis of the enthalpy and melting temperature effect on the inside building comfort sensation potential of the plastering PCM.

SET Characteristics of Phase Change Bridge Devices

2008 ◽  
Vol 1072 ◽  
Author(s):  
Daniel Krebs ◽  
Simone Raoux ◽  
Charles T. Rettner ◽  
Robert M. Shelby ◽  
Geoffrey W. Burr ◽  
...  
Keyword(s):  
Phase Change ◽  
Amorphous Phase ◽  
Phase Change Materials ◽  
Random Access ◽  
Stable States ◽  
Threshold Switching ◽  
Non Volatile Memory ◽  
Switching Material ◽  
The Difference ◽  
Memory Applications

ABSTRACTScaling studies have demonstrated that Phase Change Random Access Memory (PCRAM) is one of the most promising candidates for future non-volatile memory applications. The search for suitable phase change materials with optimized properties is therefore actively pursuit. In this paper, SET (crystallization) characteristics of an ultra fast switching material Ge15Sb85 in phase change memory bridge cell devices are presented. It was found that reproducible switching between two stable states with one decade resistance contrast and current pulses as short as 10 ns for SET and RESET (re-amorphization) operation is possible. Particular emphasis was placed on the difference in crystallization kinetics between the as-deposited and melt-quenched amorphous phase. Evidence is given for the existence of an electrical field as the critical parameter for threshold switching rather than a threshold voltage. For Ge15Sb85 a threshold switching field of 9MV/m was measured and it was shown that switching from the melt-quenched amorphous phase to the crystalline phase is about 600 times faster than crystallization from the as-deposited amorphous phase.

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