Thermoelectric Characterization of Ge2Sb2Te5 Films for Phase-Change Memory

2012 ◽  
Author(s):  
Jaeho Lee ◽  
Takashi Kodama ◽  
Yoonjin Won ◽  
Mehdi Asheghi ◽  
Kenneth E. Goodson
Keyword(s):  
Seebeck Coefficient ◽  
Phase Change ◽  
Thermoelectric Properties ◽  
Phase Change Materials ◽  
Phase Change Memory ◽  
Film Structure ◽  
Thermoelectric Effects ◽  
Crystallization Effect ◽  
Change Memory

While thermoelectric effects can strongly influence the performance of phase-change memory (PCM), the thermoelectric properties of phase-change materials for thin film structure have received little attention. This work reports the temperature and phase dependent Seebeck coefficient of 25 nm and 125 nm thick Ge2Sb2Te5 (GST) films. The Seebeck coefficient of crystalline GST films varies strongly with film thickness, due to changes in crystallization effect and grain boundary scattering. Electrothermal simulations demonstrate that the measured thermoelectric properties can strongly influence the temperature distribution and figures of merit for PCM devices. These data will facilitate cell optimization of novel phase-change memories.

Numerical Modeling of Thermoelectric Thomson Effect in Phase Change Memory Bridge Structures

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1450004 ◽  
Author(s):  
Faruk Dirisaglik ◽  
Gokhan Bakan ◽  
Azer Faraclas ◽  
Ali Gokirmak ◽  
Helena Silva
Keyword(s):  
Numerical Modeling ◽  
Phase Change ◽  
Phase Change Materials ◽  
Phase Change Memory ◽  
Thermoelectric Effects ◽  
Non Volatile Memory ◽  
Bridge Structures ◽  
P Type ◽  
Electrothermal Effects ◽  
Change Memory

Phase change memory is a non-volatile memory technology that utilizes the electrical resistivity contrast between resistive amorphous and conductive crystalline phases of phase change materials. These devices operate at high current densities and high temperature gradients which lead to significant thermoelectric effects. We have performed numerical modeling of electrothermal effects in p-type Ge2Sb2Te5 phase change memory structures suspended on TiN contact pads using COMSOL Multiphysics. Temperature dependent material parameters are used in the model. Strong asymmetry is observed in temperature profiles in all cases: the hottest spot appears closer to the higher potential end suggesting that the thermal profile can be significantly altered by the thermoelectric effects during device operation. Hence, thermoelectric effects need to be considered for device designs for lower power and higher reliability devices.

scholarly journals Scalability of Phase Change Materials in Nanostructure Template

2015 ◽  
Vol 2015 ◽  
pp. 1-4
Author(s):  
Wei Zhang ◽  
Biyun L. Jackson ◽  
Ke Sun ◽  
Jae Young Lee ◽  
Shyh-Jer Huang ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Scaling Limit ◽  
Phase Change Memory ◽  
Leakage Power ◽  
Memory Element ◽  
Transmission Electron ◽  
Diffraction Mode ◽  
Memory Applications ◽  
Change Memory

The scalability of In2Se3, one of the phase change materials, is investigated. By depositing the material onto a nanopatterned substrate, individual In2Se3nanoclusters are confined in the nanosize pits with well-defined shape and dimension permitting the systematic study of the ultimate scaling limit of its use as a phase change memory element. In2Se3of progressively smaller volume is heated inside a transmission electron microscope operating in diffraction mode. The volume at which the amorphous-crystalline transition can no longer be observed is taken as the ultimate scaling limit, which is approximately 5 nm3for In2Se3. The physics for the existence of scaling limit is discussed. Using phase change memory elements in memory hierarchy is believed to reduce its energy consumption because they consume zero leakage power in memory cells. Therefore, the phase change memory applications are of great importance in terms of energy saving.

Dynamic Resistance—A Metric for Variability Characterization of Phase-Change Memory

2009 ◽  
Vol 30 (2) ◽  
pp. 126-129 ◽  
Author(s):  
B. Rajendran ◽  
M. Breitwisch ◽  
Ming-Hsiu Lee ◽  
G.W. Burr ◽  
Yen-Hao Shih ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Memory ◽  
Dynamic Resistance ◽  
Change Memory

Phase change materials and phase change memory

MRS Bulletin ◽  
2014 ◽  
Vol 39 (8) ◽  
pp. 703-710 ◽  
Author(s):  
Simone Raoux ◽  
Feng Xiong ◽  
Matthias Wuttig ◽  
Eric Pop
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Phase Change Memory ◽  
Image Position ◽  
Change Memory

Abstract

Design of an Initialization Circuit Used in Phase Change Memory Chip

2014 ◽  
Vol 543-547 ◽  
pp. 471-474
Author(s):  
Qian Wang ◽  
Hou Peng Chen ◽  
Yi Yun Zhang ◽  
Xi Fan ◽  
Xi Li ◽  
...  
Keyword(s):  
Phase Change ◽  
High Resistance ◽  
Phase Change Materials ◽  
Phase Change Memory ◽  
Memory Cells ◽  
Memory Chip ◽  
Grain Sizes ◽  
Reset Operation ◽  
Materials Used ◽  
Change Memory

Design of a novel initialization circuit is presented in this paper. The initialization circuit is used to supply initialization current to the first test of phase change memory chip after delivery. Inhomogeneous crystalline grain sizes appear in phase change materials used in memory cells during manufacturing process. The crystalline phase with low resistance will convert to amorphous phase with high resistance after initialization, which is called RESET the memory cells to 0. Normal RESET operation current is not high enough to RESET great grain, which deteriorates bit yield of phase change memory chip. In comparison, the higher initialization current will increase bit yield observably.

Investigation of Time Instability Factors in Ti-SbxTe Based Phase Change Memory

2013 ◽  
Vol 873 ◽  
pp. 825-830 ◽  
Author(s):  
Xing Long Ji ◽  
Liang Cai Wu ◽  
Feng Rao ◽  
Zhi Tang Song ◽  
Min Zhu ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Crystallization Process ◽  
Phase Change Memory ◽  
Structure Model ◽  
Data Retention ◽  
Spontaneous Crystallization ◽  
Change Trend ◽  
Band Structure Model ◽  
Change Memory

In this paper, the two time instability factors in phase change memory, amorphous resistance drift and spontaneous crystallization process, are studied based on Ti2.75(SbxTe)97.25 and Ti6.85(SbxTe)93.15. The drift coefficients of both components are calculated and compared under room temperature. The reason why the drift coefficient decreases with the Ti concentration increases is discussed based on the band structure model of amorphous phase change materials. And the data retention change trend is also presented. The experiment results and the physical explaination can also be extended to other metallic element doped SbxTe alloy phase change materials.

Phase transition characteristics of Al-Sb phase change materials for phase change memory application

2013 ◽  
Vol 103 (7) ◽  
pp. 072114 ◽  
Author(s):  
Xilin Zhou ◽  
Liangcai Wu ◽  
Zhitang Song ◽  
Feng Rao ◽  
Kun Ren ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Change ◽  
Phase Change Materials ◽  
Phase Change Memory ◽  
Change Memory
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