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.

Structural transition pathway and bipolar switching of the GeTe–Sb2Te3 superlattice as interfacial phase-change memory

2019 ◽  
Vol 213 ◽  
pp. 303-319 ◽  
Author(s):  
Nobuki Inoue ◽  
Hisao Nakamura
Keyword(s):  
Phase Change ◽  
High Resistance ◽  
Structural Transition ◽  
Phase Change Memory ◽  
High Resistance State ◽  
Interfacial Phase ◽  
Bipolar Switching ◽  
Resistance State ◽  
Change Memory ◽  
Resistive Switching Mechanism

We investigated the resistive switching mechanism between the high-resistance state (HRS) and the low-resistance state (LRS) of the GeTe–Sb2Te3 (GST) superlattice.

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.

A Novel Programming Technique to Boost Low-Resistance State Performance in Ge-Rich GST Phase Change Memory

2014 ◽  
Vol 61 (5) ◽  
pp. 1246-1254 ◽  
Author(s):  
Athanasios Kiouseloglou ◽  
Gabriele Navarro ◽  
Veronique Sousa ◽  
Alain Persico ◽  
Anne Roule ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Memory ◽  
Programming Technique ◽  
Low Resistance ◽  
Resistance State ◽  
Change Memory

Calculations of Absorbed Dose in Heavy-Ion Irradiated Phase-Change Memory Cells

2014 ◽  
Vol 906 ◽  
pp. 81-88
Author(s):  
Nevena Zdjelarević ◽  
Ljubinko Timotijević ◽  
Radeta Marić ◽  
Koviljka Stanković ◽  
Miloš Vujisić
Keyword(s):  
Phase Change ◽  
Active Layer ◽  
Ion Irradiation ◽  
Phase Change Memory ◽  
Absorbed Dose ◽  
Memory Cell ◽  
Heavy Ion ◽  
Heavy Ion Irradiation ◽  
Sandwiched Structure ◽  
Change Memory

Heavy ion irradiation on phase change memory cell was conducted using Monte Carlo simulations. Absorbed dose in the whole memory cell, as well as in its active layer was assessed. Phase change memory cell was modeled as a sandwiched structure of two TiW electrodes and ZnS-SiO2 films as insulators surrounding the active region. The most commonly used phase change material, Ge2Sb2Te5, was used as active layer of the cell. Ionization effects of heavy ion irradiation were investigated for various thicknesses of phase change layer and different ion energies.

Controllable multilevel resistance state of superlattice-like GaSb/Ge2Te films for ultralong retention phase-change memory

2018 ◽  
Vol 481 ◽  
pp. 110-115 ◽  
Author(s):  
Zengguang Li ◽  
Yegang Lu ◽  
Miao Wang ◽  
Xiang Shen ◽  
Xianghua Zhang ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Memory ◽  
Resistance State ◽  
Change Memory

Defect Engineering in Antimony Telluride Phase-Change Materials

2019 ◽  
Vol 944 ◽  
pp. 607-612
Author(s):  
Yong Wang ◽  
Kun Ren ◽  
San Nian Song ◽  
Zhi Tang Song
Keyword(s):  
Ion Implantation ◽  
Power Consumption ◽  
Phase Change ◽  
Physical Vapor Deposition ◽  
Hexagonal Phase ◽  
Rapid Development ◽  
Phase Change Memory ◽  
Face Centered Cubic ◽  
Fcc Phase ◽  
Change Memory

In the past 20 years, the phase-change memory technology has achieved rapid development, of which alloys along the GeTe-Sb2Te3 pseudobinary line are the most extensively researched materials. In recent years, Sb2Te3-based materials start to attract the attention of researchers. A recent study has shown that the Sb2Te3 (ST) material has a face-centered cubic (Fcc) phase which contains a high concentration of vacancies at low temperature. Due to the poor amorphous thermal stability of ST, the as-deposited film obtained by physical vapor deposition is crystalline (Fcc phase). Therefore, we proposed a vacancy control mechanism, using inert gas Ar to ion implantation of as-deposited ST films, redistributing vacancies in the as-deposited ST films. Through different doses of Ar ion implantation, we obtain amorphous ST materials with different resistivity. We find that after the injection dose reached 1 × 1016 cm-2, the effect of continued increase in the implantation dose on the resistivity of the thin film is negligible. After ion implantation, the transition temperature of the metastable Fcc phase to the hexagonal phase (Hex) is increased, which is beneficial to improve the power consumption and endurance of the device. The ST which is injected with a dose of 1 × 1016 cm−2 Ar ion based phase-change memory cell can perform erasing operation in 100 ns, showing low power consumption potential. Our work provides a new idea and method for the application of future defect control in phase-change memory research.

Bilayer Ga-Sb Phase Change Memory with Intermediate Resistance State

2021 ◽  
Author(s):  
Haibo Gong ◽  
Rubab Ume ◽  
Vadim Tokranov ◽  
Michael Yakimov ◽  
Devendra Sadana ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Memory ◽  
Intermediate Resistance ◽  
Resistance State ◽  
Change Memory

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.

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