1
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Shen J, Song W, Ren K, Song Z, Zhou P, Zhu M. Toward the Speed Limit of Phase-Change Memory. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208065. [PMID: 36719053 DOI: 10.1002/adma.202208065] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 01/16/2023] [Indexed: 06/18/2023]
Abstract
Phase-change memory (PCM) is one of the most promising candidates for next-generation data-storage technology, the programming speed of which has enhanced within a timescale from milliseconds to sub-nanosecond (≈500 ps) through decades of effort. As the potential applications of PCM strongly depend on the switching speed, namely, the time required for the recrystallization of amorphous chalcogenide media, the finding of the ultimate crystallization speed is of great importance both theoretically and practically. In this work, through systematic analysis of discovered phase-change materials and ab initio molecular dynamics simulations, elemental Sb-based PCM is predicted to have a superfast crystallization speed. Indeed, such cells experimentally present extremely fast crystallization speeds within 360 ps. Remarkably, the recrystallization process is further sped up as the device shrinks, and a record-fast crystallization speed of only 242 ps is achieved in 60 nm-size devices. These findings open opportunities for dynamic random-access memory (DRAM)-like and even cache-like PCM using appropriate storage materials.
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Affiliation(s)
- Jiabin Shen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
- State Key Laboratory of ASIC and System Department of Microelectronics, Fudan University, Shanghai, 200433, P. R. China
| | - Wenxiong Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
| | - Kun Ren
- College of Micro-Nano Electronics, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
| | - Peng Zhou
- State Key Laboratory of ASIC and System Department of Microelectronics, Fudan University, Shanghai, 200433, P. R. China
| | - Min Zhu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
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2
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Shao M, Qiao Y, Xue Y, Song S, Song Z, Li X. Advantages of Ta-Doped Sb 3Te 1 Materials for Phase Change Memory Applications. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:633. [PMID: 36839001 PMCID: PMC9966191 DOI: 10.3390/nano13040633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/29/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Phase change memory (PCM), a typical representative of new storage technologies, offers significant advantages in terms of capacity and endurance. However, among the research on phase change materials, thermal stability and switching speed performance have always been the direction where breakthroughs are needed. In this research, as a high-speed and good thermal stability material, Ta was proposed to be doped in Sb3Te1 alloy to improve the phase transition performance and electrical properties. The characterization shows that Ta-doped Sb3Te1 can crystallize at temperatures up to 232 °C and devices can operate at speeds of 6 ns and 8 × 104 operation cycles. The reduction of grain size and the density change rate (3.39%) show excellent performances, which are both smaller than that of Ge2Sb2Te5 (GST) and Sb3Te1. These properties conclusively demonstrate that Ta incorporation of Sb3Te1 alloy is a material with better thermal stability and faster crystallization rates for PCM applications.
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Affiliation(s)
- Mingyue Shao
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Qiao
- The Microelectronic Research & Development Center, Shanghai University, Shanghai 200444, China
| | - Yuan Xue
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sannian Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaodan Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Shen J, Jia S, Shi N, Ge Q, Gotoh T, Lv S, Liu Q, Dronskowski R, Elliott SR, Song Z, Zhu M. Elemental electrical switch enabling phase segregation-free operation. Science 2021; 374:1390-1394. [PMID: 34882462 DOI: 10.1126/science.abi6332] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Jiabin Shen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050 Shanghai, China.,University of the Chinese Academy of Sciences, Beijing 100029, China
| | - Shujing Jia
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050 Shanghai, China.,University of the Chinese Academy of Sciences, Beijing 100029, China
| | - Nannan Shi
- Thermo Fisher Scientific China, Shanghai 200050, China
| | - Qingqin Ge
- Thermo Fisher Scientific China, Shanghai 200050, China
| | - Tamihiro Gotoh
- Department of Physics, Graduate School of Science and Technology, Gunma University, Maebashi 3718510, Japan
| | - Shilong Lv
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050 Shanghai, China
| | - Qi Liu
- Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
| | - Richard Dronskowski
- Institute of Inorganic Chemistry, Chair of Solid-State and Quantum Chemistry, RWTH Aachen University, Aachen 52056, Germany
| | - Stephen R Elliott
- Trinity College, University of Cambridge, Cambridge CB2 1TQ, UK.,Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050 Shanghai, China
| | - Min Zhu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050 Shanghai, China
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4
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Multi-level phase-change memory with ultralow power consumption and resistance drift. Sci Bull (Beijing) 2021; 66:2217-2224. [PMID: 36654113 DOI: 10.1016/j.scib.2021.07.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/02/2021] [Accepted: 07/07/2021] [Indexed: 01/20/2023]
Abstract
By controlling the amorphous-to-crystalline relative volume, chalcogenide phase-change memory materials can provide multi-level data storage (MLS), which offers great potential for high-density storage-class memory and neuro-inspired computing. However, this type of MLS system suffers from high power consumption and a severe time-dependent resistance increase ("drift") in the amorphous phase, which limits the number of attainable storage levels. Here, we report a new type of MLS system in yttrium-doped antimony telluride, utilizing reversible multi-level phase transitions between three states, i.e., amorphous, metastable cubic and stable hexagonal crystalline phases, with ultralow power consumption (0.6-4.3 pJ) and ultralow resistance drift for the lower two states (power-law exponent < 0.007). The metastable cubic phase is stabilized by yttrium, while the evident reversible cubic-to-hexagonal transition is attributed to the sequential and directional migration of Sb atoms. Finally, the decreased heat dissipation of the material and the increase in crystallinity contribute to the overall high performance. This study opens a new way to achieve advanced multi-level phase-change memory without the need for complicated manufacturing procedures or iterative programming operations.
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5
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Effect of Nitrogen Doping on the Crystallization Kinetics of Ge 2Sb 2Te 5. NANOMATERIALS 2021; 11:nano11071729. [PMID: 34209198 PMCID: PMC8308197 DOI: 10.3390/nano11071729] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/25/2021] [Accepted: 06/28/2021] [Indexed: 11/17/2022]
Abstract
Among the phase change materials, Ge2Sb2Te5 (GST-225) is the most studied and is already integrated into many devices. N doping is known to significantly improve some key characteristics such as the thermal stability of materials and the resistance drift of devices. However, the origin, at the atomic scale, of these alterations is rather elusive. The most important issue is to understand how N doping affects the crystallization characteristics, mechanisms and kinetics, of GST-225. Here, we report the results of a combination of in situ and ex situ transmission electron microscopy (TEM) investigations carried out on specifically designed samples to evidence the influence of N concentration on the crystallization kinetics and resulting morphology of the alloy. Beyond the known shift of the crystallization temperature and the observation of smaller grains, we show that N renders the crystallization process more "nucleation dominated" and ascribe this characteristic to the increased viscosity of the amorphous state. This increased viscosity is linked to the mechanical rigidity and the reduced diffusivity resulting from the formation of Ge-N bonds in the amorphous phase. During thermal annealing, N hampers the coalescence of the crystalline grains and the cubic to hexagonal transition. Making use of AbStrain, a recently invented TEM-based technique, we evidence that the nanocrystals formed from the crystallization of N-doped amorphous GST-225 are under tension, which suggests that N is inserted in the lattice and explains why it is not found at grain boundaries. Globally, all these results demonstrate that the origin of the effect of N on the crystallization of GST-225 is not attributed to the formation of a secondary phase such as a nitride, but to the ability of N to bind to Ge in the amorphous and crystalline phases and to unbind and rebind with Ge along the diffusion path of this atomic species during annealing.
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6
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Saxena N, Raghunathan R, Manivannan A. A scheme for enabling the ultimate speed of threshold switching in phase change memory devices. Sci Rep 2021; 11:6111. [PMID: 33731824 PMCID: PMC7969762 DOI: 10.1038/s41598-021-85690-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/04/2021] [Indexed: 11/09/2022] Open
Abstract
Phase change materials exhibit threshold switching (TS) that establishes electrical conduction through amorphous material followed by Joule heating leading to its crystallization (set). However, achieving picosecond TS is one of the key challenges for realizing non-volatile memory operations closer to the speed of computing. Here, we present a trajectory map for enabling picosecond TS on the basis of exhaustive experimental results of voltage-dependent transient characteristics of Ge2Sb2Te5 phase-change memory (PCM) devices. We demonstrate strikingly faster switching, revealing an extraordinarily low delay time of less than 50 ps for an over-voltage equal to twice the threshold voltage. Moreover, a constant device current during the delay time validates the electronic nature of TS. This trajectory map will be useful for designing PCM device with SRAM-like speed.
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Affiliation(s)
- Nishant Saxena
- Phase Change Memory Lab, Advanced Memory and Computing Group, Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Rajamani Raghunathan
- UGC-DAE Consortium for Scientific Research, DAVV Campus, Khandwa Road, Indore, Madhya Pradesh, 452001, India
| | - Anbarasu Manivannan
- Phase Change Memory Lab, Advanced Memory and Computing Group, Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
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7
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Liu B, Liu W, Li Z, Li K, Wu L, Zhou J, Song Z, Sun Z. Y-Doped Sb 2Te 3 Phase-Change Materials: Toward a Universal Memory. ACS APPLIED MATERIALS & INTERFACES 2020; 12:20672-20679. [PMID: 32283921 DOI: 10.1021/acsami.0c03027] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The disadvantages of high power consumption and slow operating speed hinder the application of phase-change materials (PCMs) for a universal memory. In this work, based on a rigorous experimental scheme, we synthesized a series of YxSb2-xTe3 (0 ≤ x ≤ 0.333) PCMs and demonstrated that Y0.25Sb1.75Te3 (YST) is an excellent candidate material for the universal phase-change memory. This YST PCM, even being integrated into a conventional T-shaped device, exhibits an ultralow reset power consumption of 1.3 pJ and a competitive fast set speed of 6 ns. The ultralow power consumption is attributed to the Y-reduced thermal and electrical conductivity, while the maintained crystal structure of Sb2Te3 and the grain refinement provide the competitive fast crystallization speed. This work highlights a novel way to obtain new PCMs with lower power consumption and competitive fast speed toward a universal memory.
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Affiliation(s)
- Bin Liu
- School of Materials Science and Engineering and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Wanliang Liu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Zhen Li
- School of Materials Science and Engineering and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Kaiqi Li
- School of Materials Science and Engineering and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Liangcai Wu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Jian Zhou
- School of Materials Science and Engineering and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Zhimei Sun
- School of Materials Science and Engineering and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China
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8
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Chen X, Zheng Y, Zhu M, Ren K, Wang Y, Li T, Liu G, Guo T, Wu L, Liu X, Cheng Y, Song Z. Scandium doping brings speed improvement in Sb 2Te alloy for phase change random access memory application. Sci Rep 2018; 8:6839. [PMID: 29717216 PMCID: PMC5931567 DOI: 10.1038/s41598-018-25215-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/17/2018] [Indexed: 11/09/2022] Open
Abstract
Phase change random access memory (PCRAM) has gained much attention as a candidate for nonvolatile memory application. To develop PCRAM materials with better properties, especially to draw closer to dynamic random access memory (DRAM), the key challenge is to research new high-speed phase change materials. Here, Scandium (Sc) has been found it is helpful to get high-speed and good stability after doping in Sb2Te alloy. Sc0.1Sb2Te based PCRAM cell can achieve reversible switching by applying even 6 ns voltage pulse experimentally. And, Sc doping not only promotes amorphous stability but also improves the endurance ability comparing with pure Sb2Te alloy. Moreover, according to DFT calculations, strong Sc-Te bonds lead to the rigidity of Sc centered octahedrons, which may act as crystallization precursors in recrystallization process to boost the set speed.
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Affiliation(s)
- Xin Chen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yonghui Zheng
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Min Zhu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Kun Ren
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Yong Wang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Tao Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Guangyu Liu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Tianqi Guo
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Lei Wu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Xianqiang Liu
- Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - Yan Cheng
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China. .,Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, 200062, China.
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
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9
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Shukla KD, Saxena N, Manivannan A. An ultrafast programmable electrical tester for enabling time-resolved, sub-nanosecond switching dynamics and programming of nanoscale memory devices. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:123906. [PMID: 29289189 DOI: 10.1063/1.4999522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent advancements in commercialization of high-speed non-volatile electronic memories including phase change memory (PCM) have shown potential not only for advanced data storage but also for novel computing concepts. However, an in-depth understanding on ultrafast electrical switching dynamics is a key challenge for defining the ultimate speed of nanoscale memory devices that demands for an unconventional electrical setup, specifically capable of handling extremely fast electrical pulses. In the present work, an ultrafast programmable electrical tester (PET) setup has been developed exceptionally for unravelling time-resolved electrical switching dynamics and programming characteristics of nanoscale memory devices at the picosecond (ps) time scale. This setup consists of novel high-frequency contact-boards carefully designed to capture extremely fast switching transient characteristics within 200 ± 25 ps using time-resolved current-voltage measurements. All the instruments in the system are synchronized using LabVIEW, which helps to achieve various programming characteristics such as voltage-dependent transient parameters, read/write operations, and endurance test of memory devices systematically using short voltage pulses having pulse parameters varied from 1 ns rise/fall time and 1.5 ns pulse width (full width half maximum). Furthermore, the setup has successfully demonstrated strikingly one order faster switching characteristics of Ag5In5Sb60Te30 (AIST) PCM devices within 250 ps. Hence, this novel electrical setup would be immensely helpful for realizing the ultimate speed limits of various high-speed memory technologies for future computing.
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Affiliation(s)
- Krishna Dayal Shukla
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore 453552, India
| | - Nishant Saxena
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore 453552, India
| | - Anbarasu Manivannan
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore 453552, India
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10
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Controllable crystal growth and fast reversible crystallization-to-amorphization in Sb 2Te-TiO 2 films. Sci Rep 2017; 7:46279. [PMID: 28397858 PMCID: PMC5387738 DOI: 10.1038/srep46279] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 03/13/2017] [Indexed: 11/08/2022] Open
Abstract
The structure evolution and crystallization processes of Sb2Te-TiO2 films have been investigated. The Sb2Te-rich nanocrystals, surrounded by TiO2 amorphous phases, are observed in the annealed Sb2Te-TiO2 composite films. The segregated domains exhibit obvious chalcogenide/TiOx interfaces, which elevate crystallization temperature, impede the grain growth and increase crystalline resistance. Compared with that in conventional Ge2Sb2Te5 film, the shorter time for onset crystallization (25 ns) and amorphization (100 ns) has been achieved in as-deposited (Sb2Te)94.7(TiO2)5.3 film under 60 mW laser irradiation. The corresponding recrystallization and re-amorphization can also be realized in the film. From Johnson-Mehl-Avrami (JMA) analysis, it is further found that the one-dimensional grain growth with controlled interface is dominant for the film during the fast phase-change process. Therefore, (Sb2Te)94.7(TiO2)5.3 film with improved crystallization mechanism is promising for high-stable and fast-speed memory applications.
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11
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Shukla KD, Saxena N, Durai S, Manivannan A. Redefining the Speed Limit of Phase Change Memory Revealed by Time-resolved Steep Threshold-Switching Dynamics of AgInSbTe Devices. Sci Rep 2016; 6:37868. [PMID: 27886266 PMCID: PMC5122954 DOI: 10.1038/srep37868] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 10/28/2016] [Indexed: 11/10/2022] Open
Abstract
Although phase-change memory (PCM) offers promising features for a 'universal memory' owing to high-speed and non-volatility, achieving fast electrical switching remains a key challenge. In this work, a correlation between the rate of applied voltage and the dynamics of threshold-switching is investigated at picosecond-timescale. A distinct characteristic feature of enabling a rapid threshold-switching at a critical voltage known as the threshold voltage as validated by an instantaneous response of steep current rise from an amorphous off to on state is achieved within 250 picoseconds and this is followed by a slower current rise leading to crystallization. Also, we demonstrate that the extraordinary nature of threshold-switching dynamics in AgInSbTe cells is independent to the rate of applied voltage unlike other chalcogenide-based phase change materials exhibiting the voltage dependent transient switching characteristics. Furthermore, numerical solutions of time-dependent conduction process validate the experimental results, which reveal the electronic nature of threshold-switching. These findings of steep threshold-switching of 'sub-50 ps delay time', opens up a new way for achieving high-speed non-volatile memory for mainstream computing.
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Affiliation(s)
- Krishna Dayal Shukla
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore - 453552, India
| | - Nishant Saxena
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore - 453552, India
| | - Suresh Durai
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore - 453552, India
| | - Anbarasu Manivannan
- Discipline of Electrical Engineering, Indian Institute of Technology Indore, Indore - 453552, India.,Materials Science and Engineering, Indian Institute of Technology Indore, Indore - 453552, India
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12
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Guo S, Xu L, Zhang J, Hu Z, Li T, Wu L, Song Z, Chu J. Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences. Sci Rep 2016; 6:33639. [PMID: 27640336 PMCID: PMC5027526 DOI: 10.1038/srep33639] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/31/2016] [Indexed: 11/09/2022] Open
Abstract
The optical properties and structural variations of silicon (Si) doped Sb2Te (SST) films as functions of temperature (210–620 K) and Si concentration (0–33%) have been investigated by the means of temperature dependent Raman scattering and spectroscopic ellipsometry experiments. Based upon the changes in Raman phonon modes and dielectric functions, it can be concluded that the temperature ranges for intermediates and transition states are estimated to 150, 120, 90, and 0 K, corresponding to ST, SST25%, SST28%, and SST33% films, respectively. The phenomenon also can be summarized by the thermal evolutions of interband electronic transition energies (En) and partial spectral weight integral (I). The disappearance of intermediate (INT) state for SST33% film between amorphous (AM) and hexagonal (HEX) phases can be attributed to the acceleratory crystallization of HEX phase by Si introduction. It illustrates that the risk of phase separation (Sb and Te) during the cyclic phase-change processes decreases with the increasing Si concentration. The enhanced crystallization behaviors can optimize the data retention ability and the long term stability of ST by Si doping, which are important indicators for phase change materials. The performance improvement has been analyzed qualitatively from the optical perspective.
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Affiliation(s)
- Shuang Guo
- Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
| | - Liping Xu
- Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
| | - Jinzhong Zhang
- Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
| | - Zhigao Hu
- Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
| | - Tao Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Liangcai Wu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Junhao Chu
- Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
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13
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Kalikka J, Zhou X, Dilcher E, Wall S, Li J, Simpson RE. Strain-engineered diffusive atomic switching in two-dimensional crystals. Nat Commun 2016; 7:11983. [PMID: 27329563 PMCID: PMC4917972 DOI: 10.1038/ncomms11983] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 05/18/2016] [Indexed: 11/10/2022] Open
Abstract
Strain engineering is an emerging route for tuning the bandgap, carrier mobility, chemical reactivity and diffusivity of materials. Here we show how strain can be used to control atomic diffusion in van der Waals heterostructures of two-dimensional (2D) crystals. We use strain to increase the diffusivity of Ge and Te atoms that are confined to 5 Å thick 2D planes within an Sb2Te3–GeTe van der Waals superlattice. The number of quintuple Sb2Te3 2D crystal layers dictates the strain in the GeTe layers and consequently its diffusive atomic disordering. By identifying four critical rules for the superlattice configuration we lay the foundation for a generalizable approach to the design of switchable van der Waals heterostructures. As Sb2Te3–GeTe is a topological insulator, we envision these rules enabling methods to control spin and topological properties of materials in reversible and energy efficient ways. Strain engineering allows design of materials with tailored properties. Here, the authors show that strain can be used to control atomic diffusion in Sb2Te3-GeTe superlattices, and they propose general design rules to enable atomic switching functionalities in van der Waals heterostructures.
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Affiliation(s)
- Janne Kalikka
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372, Singapore.,Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA
| | - Xilin Zhou
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372, Singapore
| | - Eric Dilcher
- Institut de Ciencies Fotoniques (ICFO), Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Simon Wall
- Institut de Ciencies Fotoniques (ICFO), Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Ju Li
- Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA
| | - Robert E Simpson
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372, Singapore
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14
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Ji X, Wu L, Zhu M, Rao F, Song Z, Hu Z, Guo S, Xu L, Zhou X, Feng S. Titanium-induced structure modification for thermal stability enhancement of a GeTeTi phase change material. RSC Adv 2015. [DOI: 10.1039/c4ra11504j] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
For GTT, just with a small Ti fraction, the amorphous stability is greatly enhanced, and the grain size decreases one order of magnitude. This can be attributed to the structure modification induced by the Ti-center units.
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15
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One order of magnitude faster phase change at reduced power in Ti-Sb-Te. Nat Commun 2014; 5:4086. [PMID: 25001009 PMCID: PMC4102114 DOI: 10.1038/ncomms5086] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 05/09/2014] [Indexed: 11/08/2022] Open
Abstract
To date, slow Set operation speed and high Reset operation power remain to be important limitations for substituting dynamic random access memory by phase change memory. Here, we demonstrate phase change memory cell based on Ti0.4Sb2Te3 alloy, showing one order of magnitude faster Set operation speed and as low as one-fifth Reset operation power, compared with Ge2Sb2Te5-based phase change memory cell at the same size. The enhancements may be rooted in the common presence of titanium-centred octahedral motifs in both amorphous and crystalline Ti0.4Sb2Te3 phases. The essentially unchanged local structures around the titanium atoms may be responsible for the significantly improved performance, as these structures could act as nucleation centres to facilitate a swift, low-energy order-disorder transition for the rest of the Sb-centred octahedrons. Our study may provide an alternative to the development of high-speed, low-power dynamic random access memory-like phase change memory technology.
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16
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Jeyasingh R, Fong SW, Lee J, Li Z, Chang KW, Mantegazza D, Asheghi M, Goodson KE, Wong HSP. Ultrafast characterization of phase-change material crystallization properties in the melt-quenched amorphous phase. NANO LETTERS 2014; 14:3419-26. [PMID: 24798660 DOI: 10.1021/nl500940z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Phase change materials are widely considered for application in nonvolatile memories because of their ability to achieve phase transformation in the nanosecond time scale. However, the knowledge of fast crystallization dynamics in these materials is limited because of the lack of fast and accurate temperature control methods. In this work, we have developed an experimental methodology that enables ultrafast characterization of phase-change dynamics on a more technologically relevant melt-quenched amorphous phase using practical device structures. We have extracted the crystallization growth velocity (U) in a functional capped phase change memory (PCM) device over 8 orders of magnitude (10(-10) < U < 10(-1) m/s) spanning a wide temperature range (415 < T < 580 K). We also observed direct evidence of non-Arrhenius crystallization behavior in programmed PCM devices at very high heating rates (>10(8) K/s), which reveals the extreme fragility of Ge2Sb2Te5 in its supercooled liquid phase. Furthermore, these crystallization properties were studied as a function of device programming cycles, and the results show degradation in the cell retention properties due to elemental segregation. The above experiments are enabled by the use of an on-chip fast heater and thermometer called as microthermal stage (MTS) integrated with a vertical phase change memory (PCM) cell. The temperature at the PCM layer can be controlled up to 600 K using MTS and with a thermal time constant of 800 ns, leading to heating rates ∼10(8) K/s that are close to the typical device operating conditions during PCM programming. The MTS allows us to independently control the electrical and thermal aspects of phase transformation (inseparable in a conventional PCM cell) and extract the temperature dependence of key material properties in real PCM devices.
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Affiliation(s)
- Rakesh Jeyasingh
- Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States
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