High Temperature Thermal Characterization of Ge2Sb2Te5 for Phase Change Memory

2011 ◽  
Author(s):  
Jaeho Lee ◽  
John P. Reifenberg ◽  
Mehdi Asheghi ◽  
Kenneth E. Goodson
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Phase Change Memory ◽  
Thermal Characterization ◽  
Short Time Scale ◽  
Face Centered Cubic ◽  
Face Centered ◽  
Short Time ◽  
Change Memory

We propose a novel design of Joule heating thermometry to measure thermal properties of Ge2Sb2Te5 (GST) films at temperatures relevant for the switching of phase change memory devices. Vertically stacked micro-fabricated heaters control temperature and measure thermal conductivity of thin films using the 3ω method. The thermal time constant of the experimental structure enables studies of short time scale crystallization and cycling effects for phase change materials. This work reports the thermal conductivity of GST films from the room temperature to above 400 Celsius in amorphous, face-centered cubic, and hexagonal close-packed phases.

In-Plane Thermal Conduction and Conductivity Anisotropy in Ge2Sb2Te5 Films for Phase Change Memory

2010 ◽  
Author(s):  
Zijian Li ◽  
Jaeho Lee ◽  
John P. Reifenberg ◽  
Mehdi Asheghi ◽  
H.-S. Philip Wong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Thermal Conduction ◽  
Phase Change Memory ◽  
Conductivity Measurement ◽  
Face Centered Cubic ◽  
Free Standing ◽  
Out Of Plane ◽  
Change Memory ◽  
Thermal Conductivities

Thermal conduction governs the program/erase speed and power consumption of phase change memory (PCM) devices. This work presents the in-plane thermal conductivity measurement of Ge2Sb2Te5 (GST) films suspended in a microfabricated structure for the amorphous (a-GST), face-centered cubic (f-GST) and hexagonal close packed (h-GST) phases. The unique design of free-standing GST films eliminates the out-of-plane heat loss to the substrate and achieves high sensitivity to lateral heat conduction. The measured in-plane thermal conductivities of GST thin films are 0.18 ± 0.02 Wm−1K−1 for a-GST, 0.49 ± 0.04 Wm−1K−1 for f-GST and 1.03 ± 0.06 Wm−1K−1 for h-GST. The out-of-plane thermal conductivities are measured by using the 3ω technique. We report the in-plane thermal conductivity is 81% of the out-of-plane thermal conductivity for the crystalline phases while no anisotropy is observed for the amorphous phase. The microstructure of the GST thin film is responsible for the direction-dependent thermal conductivities.

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.

Study of the Structural Transformation of Ge2Sb2Te5 Induced by Current Pulse in Phase Change Memory

2003 ◽  
Vol 803 ◽  
Author(s):  
Rong Zhao ◽  
Tow Chong Chong ◽  
Lu Ping Shi ◽  
Pik Kie Tan ◽  
Hao Meng ◽  
...  
Keyword(s):  
Phase Change ◽  
Structural Transformation ◽  
Active Layer ◽  
High Resistance ◽  
Phase Change Memory ◽  
High Resistance State ◽  
Face Centered Cubic ◽  
Cycle Number ◽  
Resistance State ◽  
Change Memory

ABSTRACTThe electrical induced structural transformation of Ge2Sb2Te5 thin film in phase change memory device was investigated using micro-Raman spectroscopy and transmission electronic microscopy (TEM). Selected area electron diffraction (SAD) pattern showed that the electrical-induced Ge2Sb2Te5 film was crystallized into a face-centered cubic structure. Micro-Raman spectra show that the Ge2Sb2Te5 active layer at the high resistance state exhibited two minor peaks superposed on the broad peak after several switch cycles, which is identical to those of the Ge2Sb2Te5 active layer at the low resistance state. This is most likely due to the accumulation of segregated crystallites. TEM results suggest that the existence of nano-sized nuclei clusters resulted in the reduced resistance for the Ge2Sb2Te5 active layer at the high resistance state after first several switches. The dependence of resistance on the cycle number indicates that the deterioration of the Ge2Sb2Te5 active layer is resulted from the incomplete amorphization process, which is consistent with the micro-Raman results.

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

Reduction of thermal conductivity in YxSb2–xTe3 for phase change memory

2017 ◽  
Vol 122 (19) ◽  
pp. 195107 ◽  
Author(s):  
Zhen Li ◽  
Naihua Miao ◽  
Jian Zhou ◽  
Huibin Xu ◽  
Zhimei Sun
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Memory ◽  
Change Memory
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