Fluctuations, clusters, and phase transitions in liquids, solutions, and glasses: from metastable water to phase change memory materials

2013 ◽  
Vol 167 ◽  
pp. 625 ◽  
Author(s):  
C. Austen Angell ◽  
Zuofeng Zhao
Keyword(s):  
Phase Transitions ◽  
Phase Change ◽  
Phase Change Memory ◽  
Metastable Water ◽  
Change Memory

scholarly journals Structural Transitions in Ge2Sb2Te5 Phase Change Memory Thin Films Induced by Nanosecond UV Optical Pulses

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2082
Author(s):  
Mario Behrens ◽  
Andriy Lotnyk ◽  
Hagen Bryja ◽  
Jürgen W. Gerlach ◽  
Bernd Rauschenbach
Keyword(s):  
Thin Films ◽  
Phase Transitions ◽  
Phase Change ◽  
Data Storage ◽  
Structural Changes ◽  
Phase Change Memory ◽  
Phase Changes ◽  
Uv Laser ◽  
Optical Pulses ◽  
Change Memory

Ge-Sb-Te-based phase change memory alloys have recently attracted a lot of attention due to their promising applications in the fields of photonics, non-volatile data storage, and neuromorphic computing. Of particular interest is the understanding of the structural changes and underlying mechanisms induced by short optical pulses. This work reports on structural changes induced by single nanosecond UV laser pulses in amorphous and epitaxial Ge2Sb2Te5 (GST) thin films. The phase changes within the thin films are studied by a combined approach using X-ray diffraction and transmission electron microscopy. The results reveal different phase transitions such as crystalline-to-amorphous phase changes, interface assisted crystallization of the cubic GST phase and structural transformations within crystalline phases. In particular, it is found that crystalline interfaces serve as crystallization templates for epitaxial formation of metastable cubic GST phase upon phase transitions. By varying the laser fluence, GST thin films consisting of multiple phases and different amorphous to crystalline volume ratios can be achieved in this approach, offering a possibility of multilevel data storage and realization of memory devices with very low resistance drift. In addition, this work demonstrates amorphization and crystallization of GST thin films by using only one UV laser with one single pulse duration and one wavelength. Overall, the presented results offer new perspectives on switching pathways in Ge-Sb-Te-based materials and show the potential of epitaxial Ge-Sb-Te thin films for applications in advanced phase change memory concepts.

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

2008 ◽  
Vol 93 (4) ◽  
pp. 043121 ◽  
Author(s):  
W. J. Wang ◽  
L. P. Shi ◽  
R. Zhao ◽  
K. G. Lim ◽  
H. K. Lee ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Phase Change ◽  
Phase Change Memory ◽  
Memory Cells ◽  
Fast Phase ◽  
Electrical Pulses ◽  
Change Memory

scholarly journals Outlooks for development of silicon nanoparticle memory cells

2019 ◽  
Vol 5 (4) ◽  
pp. 159-164 ◽  
Author(s):  
Igor V. Talyzin ◽  
Vladimir M. Samsonov
Keyword(s):  
Molecular Dynamics ◽  
Phase Transitions ◽  
Phase Change ◽  
Silicon Nanoparticles ◽  
Phase Change Memory ◽  
Memory Cells ◽  
Silicon Nanoparticle ◽  
Change Rate ◽  
Temperature Change Rate ◽  
Change Memory

Phase change memory is based on changes in the optical, electrical or other properties of materials during phase transitions, e.g. an amorphous to crystalline transition. Currently existing and potential applications of this memory are primarily based on multicomponent alloys of metals and semiconductors. However single-component nanoparticles including Si ones are also of interest as promising nanosized memory cells. The potential for developing this type of memory cells is confirmed by the fact that the optical absorption index of bulk amorphous silicon is of the same order of magnitude as that of crystalline silicon. Certainly this phenomenon can hardly be implemented with a single nanoparticle the size of which is within light wavelength. Using molecular dynamics and the Stillinger-Weber potential we have studied the regularities of melting and the conditions of crystallization of silicon nanoparticles containing within 105 atoms. We have shown that cooling of nanosized silicon drops at a 0.2 TK/s rate or higher rates causes their amorphous transition whereas single-component nanosized metallic drops crystallize in molecular dynamics experiments even at a 1 TK/s rate. Further heating of amorphous silicon nanoparticles containing above 5 ∙ 104 atoms causes their crystallization in a specific temperature range from 1300 to 1400 K. We have concluded that there is a possibility of developing phase change memory cells on the basis of the above phase transitions. An amorphous transition of a nanoparticle can be achieved by its melting and further cooling to room temperature at a 0.2 TK/s rate whereas a crystalline transition, by its heating to 1300–1400 K at a 0.2 TK/s rate followed by cooling. Results of molecular dynamics experiments suggest there is a minimum silicon nanoparticle size for which the development of phase change memory cells becomes theoretically impossible at a given temperature change rate. For a 0.2 TK/s temperature change rate this minimum size is 12.4 nm (number of atoms approx. 5 ∙ 104).

scholarly journals 8-bit Precision In-Memory Multiplication with Projected Phase-Change Memory

2018 ◽  
Author(s):  
I. Giannopoulos ◽  
A. Sebastian ◽  
M. Le Gallo ◽  
V.P. Jonnalagadda ◽  
M. Sousa ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Memory ◽  
Change Memory

Precision of synaptic weights programmed in phase-change memory devices for deep learning inference

2020 ◽  
Author(s):  
S. R. Nandakumar ◽  
Irem Boybat ◽  
Jin-Ping Han ◽  
Stefano Ambrogio ◽  
Praneet Adusumilli ◽  
...  
Keyword(s):  
Deep Learning ◽  
Phase Change ◽  
Phase Change Memory ◽  
Memory Devices ◽  
Change Memory
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