1
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Lee C, Kim D, Lim H, Seong Y, Kim H, Park JH, Yang D, Shin HJ, Wuttig M, Choi BJ, Cho MH. Ultrahigh Stability and Operation Performance in Bi-doped GeTe/Sb 2Te 3 Superlattices Achieved by Tailoring Bonding and Structural Properties. ACS NANO 2024; 18:25625-25635. [PMID: 39223725 DOI: 10.1021/acsnano.4c06909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Changes in bond types and the reversible switching process between metavalent and covalent bonds are related to the operating mechanism of the phase-change (PC) behavior. Thus, controlling the bonding characteristics is the key to improving the PC memory performance. In this study, we have controlled the bonding characteristics of GeTe/Sb2Te3 superlattices (SLs) via bismuth (Bi) doping. The incorporation of Bi into the GeTe sublayers tailors the metavalent bond. We observed significant improvement in device reliability, set speed, and power consumption induced upon increasing Bi incorporation. The introduction of Bi was found to suppress the change in density between the SET and RESET states, resulting in a significant increase in device reliability. The reduction in Peierls distortion, leading to a more octahedral-like atomic arrangement, intensifies electron-phonon coupling with increased bond polarizability, which are responsible for the fast set speed and low power consumption. This study demonstrates how the structural and thermodynamic changes in phase change materials alter phase change characteristics due to systematic changes of bonding and provides an important methodology for the development of PC devices.
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Affiliation(s)
- Changwoo Lee
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Dasol Kim
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
- Institute of Physics, Physics of Novel Materials, RWTH Aachen University, 52056 Aachen, Germany
| | - Hyeonwook Lim
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Yeonwoo Seong
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Hyunwook Kim
- Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Ju Hwan Park
- Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Dogeon Yang
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
| | - Hee Jun Shin
- POSTECH, Pohang Accelerator Laboratory, 80, Jigokro-127-beongil, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Matthias Wuttig
- Institute of Physics, Physics of Novel Materials, RWTH Aachen University, 52056 Aachen, Germany
| | - Byung Joon Choi
- Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Mann-Ho Cho
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
- Department of System Semiconductor Engineering, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea
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2
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Shuang Y, Mori S, Yamamoto T, Hatayama S, Saito Y, Fons PJ, Song YH, Hong JP, Ando D, Sutou Y. Soret-Effect Induced Phase-Change in a Chromium Nitride Semiconductor Film. ACS NANO 2024; 18:21135-21143. [PMID: 39088786 PMCID: PMC11328172 DOI: 10.1021/acsnano.4c03574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/03/2024]
Abstract
Phase-change materials such as Ge-Sb-Te (GST) exhibiting amorphous and crystalline phases can be used for phase-change random-access memory (PCRAM). GST-based PCRAM has been applied as a storage-class memory; however, its relatively low ON/OFF ratio and the large Joule heating energy required for the RESET process (amorphization) significantly limit the storage density. This study proposes a phase-change nitride, CrN, with a much wider programming window (ON/OFF ratio more than 105) and lower RESET energy (one order of magnitude reduction from GST). High-resolution transmission electron microscopy revealed a phase-change from the low-resistance cubic CrN phase into the highly resistive hexagonal CrN2 phase induced by the Soret-effect. The proposed phase-change nitride could greatly expand the scope of conventional phase-change chalcogenides and offer a strategy for the next-generation of PCRAM, enabling a large ON/OFF ratio (∼105), low switching energy (∼100 pJ), and fast operation (∼30 ns).
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Affiliation(s)
- Yi Shuang
- WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Shunsuke Mori
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-11 Aoba-yama, Sendai 980-8579, Japan
| | - Takuya Yamamoto
- Department of Metallurgy, Graduate School of Engineering, Tohoku University, Miyagi 980-8579, Japan
| | - Shogo Hatayama
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-11 Aoba-yama, Sendai 980-8579, Japan
| | - Yuta Saito
- Device Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, Umezono 1-1-1, Tsukuba 305-8568, Japan
| | - Paul J Fons
- Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
| | - Yun-Heub Song
- Department of Electronic Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea
| | - Jin-Pyo Hong
- Department of Physics, Hanyang University, Seoul 04763, Korea
| | - Daisuke Ando
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-11 Aoba-yama, Sendai 980-8579, Japan
| | - Yuji Sutou
- WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
- Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-11 Aoba-yama, Sendai 980-8579, Japan
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3
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Qiao C, Chen L, Gu R, Liu B, Wang S, Wang S, Wang CZ, Ho KM, Xu M, Miao X. Structure, bonding and electronic characteristics of amorphous Se. Phys Chem Chem Phys 2024; 26:9510-9516. [PMID: 38450725 DOI: 10.1039/d4cp00078a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Ovonic threshold switching (OTS) selectors can effectively improve the storage density and suppress the leakage current of advanced phase-change memory devices. As a prototypical OTS material, amorphous GeSe is widely investigated. But the attention paid to amorphous Se (i.e., the functional constituent in amorphous GeSe) has been very limited up to now. Here we have explored the structure, bonding and electronic characteristics of amorphous Se using ab initio molecular dynamics simulations. The results reveal that the Se atoms in amorphous Se tend to form 2-coordinated configurations, and they connect with each other to form long chains. The fraction of the vibrational density of state located in the high frequency range is relatively large, and the formation energy of the Se-Se bond is as large as 4.44 eV, hinting that the Se-Se bonds in chains possess high stability. In addition, the mid-gap state related to the OTS behavior is also found in amorphous Se despite the small proportion. Our findings enrich the knowledge of amorphous Se, which aids the applications of Se-based OTS selectors.
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Affiliation(s)
- Chong Qiao
- School of Mathematics and Physics, Nanyang Institute of Technology, Nanyang 473004, China
| | - Lanli Chen
- School of Mathematics and Physics, Nanyang Institute of Technology, Nanyang 473004, China
| | - Rongchuan Gu
- School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Bin Liu
- School of Mathematics and Physics, Nanyang Institute of Technology, Nanyang 473004, China
| | - Shengzhao Wang
- School of Mathematics and Physics, Nanyang Institute of Technology, Nanyang 473004, China
| | - Songyou Wang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Cai-Zhuang Wang
- Ames Laboratory, U. S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Kai-Ming Ho
- Ames Laboratory, U. S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Ming Xu
- School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Xiangshui Miao
- School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan 430074, China.
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4
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Song WX, Tang Q, Zhao J, Veron M, Zhou X, Zheng Y, Cai D, Cheng Y, Xin T, Liu ZP, Song Z. Tuning the Crystallization Mechanism by Composition Vacancy in Phase Change Materials. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38498850 DOI: 10.1021/acsami.3c18538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Interface-influenced crystallization is crucial to understanding the nucleation- and growth-dominated crystallization mechanisms in phase-change materials (PCMs), but little is known. Here, we find that composition vacancy can reduce the interface energy by decreasing the coordinate number (CN) at the interface. Compared to growth-dominated GeTe, nucleation-dominated Ge2Sb2Te5 (GST) exhibits composition vacancies in the (111) interface to saturate or stabilize the Te-terminated plane. Together, the experimental and computational results provide evidence that GST prefers (111) with reduced CN. Furthermore, the (8 - n) bonding rule, rather than CN6, in the nuclei of both GeTe and GST results in lower interface energy, allowing crystallization to be observed at the simulation time in general PCMs. In comparison to GeTe, the reduced CN in the GST nuclei further decreases the interface energy, promoting faster nucleation. Our findings provide an approach to designing ultrafast phase-change memory through vacancy-stabilized interfaces.
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Affiliation(s)
- Wen-Xiong Song
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Qiongyan Tang
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Jin Zhao
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Muriel Veron
- University Grenoble Alpes, CNRS, SIMAP, 38000 Grenoble, France
| | - Xilin Zhou
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Yonghui Zheng
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Daolin Cai
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Yan Cheng
- Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Tianjiao Xin
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Zhi-Pan Liu
- Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Zhitang Song
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
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5
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Wu X, Khan AI, Lee H, Hsu CF, Zhang H, Yu H, Roy N, Davydov AV, Takeuchi I, Bao X, Wong HSP, Pop E. Novel nanocomposite-superlattices for low energy and high stability nanoscale phase-change memory. Nat Commun 2024; 15:13. [PMID: 38253559 PMCID: PMC10803317 DOI: 10.1038/s41467-023-42792-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 10/20/2023] [Indexed: 01/24/2024] Open
Abstract
Data-centric applications are pushing the limits of energy-efficiency in today's computing systems, including those based on phase-change memory (PCM). This technology must achieve low-power and stable operation at nanoscale dimensions to succeed in high-density memory arrays. Here we use a novel combination of phase-change material superlattices and nanocomposites (based on Ge4Sb6Te7), to achieve record-low power density ≈ 5 MW/cm2 and ≈ 0.7 V switching voltage (compatible with modern logic processors) in PCM devices with the smallest dimensions to date (≈ 40 nm) for a superlattice technology on a CMOS-compatible substrate. These devices also simultaneously exhibit low resistance drift with 8 resistance states, good endurance (≈ 2 × 108 cycles), and fast switching (≈ 40 ns). The efficient switching is enabled by strong heat confinement within the superlattice materials and the nanoscale device dimensions. The microstructural properties of the Ge4Sb6Te7 nanocomposite and its high crystallization temperature ensure the fast-switching speed and stability in our superlattice PCM devices. These results re-establish PCM technology as one of the frontrunners for energy-efficient data storage and computing.
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Affiliation(s)
- Xiangjin Wu
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Asir Intisar Khan
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Hengyuan Lee
- Corporate Research, Taiwan Semiconductor Manufacturing Company (TSMC), Hsinchu, Taiwan
| | - Chen-Feng Hsu
- Corporate Research, Taiwan Semiconductor Manufacturing Company (TSMC), Hsinchu, Taiwan
| | - Huairuo Zhang
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, USA
- Theiss Research, Inc., La Jolla, CA, USA
| | - Heshan Yu
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA
- School of Microelectronics, Tianjin University, Tianjin, China
| | - Neel Roy
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Albert V Davydov
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Ichiro Takeuchi
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA
| | - Xinyu Bao
- Corporate Research, Taiwan Semiconductor Manufacturing Company (TSMC), San Jose, CA, USA
| | - H-S Philip Wong
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Eric Pop
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
- Department of Materials Science & Engineering, Stanford University, Stanford, CA, USA.
- Precourt Institute for Energy, Stanford University, Stanford, CA, USA.
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6
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Schenk FM, Zellweger T, Kumaar D, Bošković D, Wintersteller S, Solokha P, De Negri S, Emboras A, Wood V, Yarema M. Phase-Change Memory from Molecular Tellurides. ACS NANO 2024; 18:1063-1072. [PMID: 38117038 PMCID: PMC10786157 DOI: 10.1021/acsnano.3c10312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 12/21/2023]
Abstract
Phase-change memory (PCM) is an emerging memory technology based on the resistance contrast between the crystalline and amorphous states of a material. Further development and realization of PCM as a mainstream memory technology rely on innovative materials and inexpensive fabrication methods. Here, we propose a generalizable and scalable solution-processing approach to synthesize phase-change telluride inks in order to meet demands for high-throughput material screening, increased energy efficiency, and advanced device architectures. Bulk tellurides, such as Sb2Te3, GeTe, Sc2Te3, and TiTe2, are dissolved and purified to obtain inks of molecular metal telluride complexes. This allowed us to unlock a wide range of solution-processed ternary tellurides by the simple mixing of binary inks. We demonstrate accurate and quantitative composition control, including prototype materials (Ge-Sb-Te) and emerging rare-earth-metal telluride-doped materials (Sc-Sb-Te). Spin-coating and annealing convert ink formulations into high-quality, phase-pure telluride films with preferred orientation along the (00l) direction. Deposition engineering of liquid tellurides enables thickness-tunable films, infilling of nanoscale vias, and film preparation on flexible substrates. Finally, we demonstrate cyclable and non-volatile prototype memory devices, achieving performance indicators such as resistance contrast and low reset energy on par with state-of-the-art sputtered PCM layers.
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Affiliation(s)
- Florian M Schenk
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Till Zellweger
- Integrated Systems Laboratory, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Dhananjeya Kumaar
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Darijan Bošković
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Simon Wintersteller
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Pavlo Solokha
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, I-16146 Genova, Italy
| | - Serena De Negri
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, I-16146 Genova, Italy
| | - Alexandros Emboras
- Integrated Systems Laboratory, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Vanessa Wood
- Materials and Device Engineering Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Maksym Yarema
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
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7
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Kim TH, Park SW, Lee HJ, Kim DH, Choi JY, Kim TG. Effect of Transition Metal Dichalcogenide Based Confinement Layers on the Performance of Phase-Change Heterostructure Memory. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2303659. [PMID: 37485593 DOI: 10.1002/smll.202303659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/04/2023] [Indexed: 07/25/2023]
Abstract
Phase-change random-access memory is a promising non-volatile memory technology. However repeated phase-change operations can cause durability issues owing to defects formed by long-distance atom diffusion. To mitigate these issues, phase-change heterostructure (PCH) devices with confinement material (CM) layers based on transition metal dichalcogenides (TMDs) such as TiTe2 have been proposed. This study implements PCH devices with additional TMDs, including NiTe2 and MoTe2 , alongside TiTe2 , and analyzes their characteristics by examining the differences in the CM layers. The results show that the NiTe2 -based PCH device demonstrates a RESET current of 1.4 mA, 38% lower than that of the TiTe2 -based device, enabling low-power operation. Furthermore, the MoTe2 -based PCH device exhibits a cycling endurance exceeding 107 cycles, a five-fold improvement in durability compare with the TiTe2 -based device. The performance differences observe in each PCH device can be attributed to the variation in the material properties, such as the cohesive energy and electrical conductivity, of the TMDs used as the CM layer. These results provide critical clues to improve the performance and reliability of conventional PCH memory devices.
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Affiliation(s)
- Tae Ho Kim
- School of Electrical Engineering, Korea University, Seoul, Seongbuk-gu, 02841, South Korea
| | - Seung Woo Park
- School of Electrical Engineering, Korea University, Seoul, Seongbuk-gu, 02841, South Korea
| | - Ho Jin Lee
- School of Electrical Engineering, Korea University, Seoul, Seongbuk-gu, 02841, South Korea
| | - Dong Hyun Kim
- School of Electrical Engineering, Korea University, Seoul, Seongbuk-gu, 02841, South Korea
| | - Jun Young Choi
- School of Electrical Engineering, Korea University, Seoul, Seongbuk-gu, 02841, South Korea
| | - Tae Geun Kim
- School of Electrical Engineering, Korea University, Seoul, Seongbuk-gu, 02841, South Korea
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8
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Shen X, Zhou Y, Zhang H, Deringer VL, Mazzarello R, Zhang W. Surface effects on the crystallization kinetics of amorphous antimony. NANOSCALE 2023; 15:15259-15267. [PMID: 37674458 DOI: 10.1039/d3nr03536k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Elemental antimony (Sb) is regarded as a promising candidate to improve the programming consistency and cycling endurance of phase-change memory and neuro-inspired computing devices. Although bulk amorphous Sb crystallizes spontaneously, the stability of the amorphous form can be greatly increased by reducing the thickness of thin films down to several nanometers, either with or without capping layers. Computational and experimental studies have explained the depressed crystallization kinetics caused by capping and interfacial confinement; however, it is unclear why amorphous Sb thin films remain stable even in the absence of capping layers. In this work, we carry out thorough ab initio molecular dynamics (AIMD) simulations to investigate the effects of free surfaces on the crystallization kinetics of amorphous Sb. We reveal a stark contrast in the crystallization behavior between bulk and surface models at 450 K, which stems from deviations from the bulk structural features in the regions approaching the surfaces. The presence of free surfaces intrinsically tends to create a sub-nanometer region where crystallization is suppressed, which impedes the incubation process and thus constrains the nucleation in two dimensions, stabilizing the amorphous phase in thin-film Sb-based memory devices.
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Affiliation(s)
- Xueyang Shen
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
| | - Yuxing Zhou
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
| | - Hanyi Zhang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
| | - Volker L Deringer
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
| | | | - Wei Zhang
- Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
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9
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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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10
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Yoo C, Jeon JW, Yoon S, Cheng Y, Han G, Choi W, Park B, Jeon G, Jeon S, Kim W, Zheng Y, Lee J, Ahn J, Cho S, Clendenning SB, Karpov IV, Lee YK, Choi JH, Hwang CS. Atomic Layer Deposition of Sb 2 Te 3 /GeTe Superlattice Film and Its Melt-Quenching-Free Phase-Transition Mechanism for Phase-Change Memory. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2207143. [PMID: 36271720 DOI: 10.1002/adma.202207143] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Atomic layer deposition (ALD) of Sb2 Te3 /GeTe superlattice (SL) film on planar and vertical sidewall areas containing TiN metal and SiO2 insulator is demonstrated. The peculiar chemical affinity of the ALD precursor to the substrate surface and the 2D nature of the Sb2 Te3 enable the growth of an in situ crystallized SL film with a preferred orientation. The SL film shows a reduced reset current of ≈1/7 of the randomly oriented Ge2 Sb2 Te5 alloy. The reset switching is induced by the transition from the SL to the (111)-oriented face-centered-cubic (FCC) Ge2 Sb2 Te5 alloy and subsequent melt-quenching-free amorphization. The in-plane compressive stress, induced by the SL-to-FCC structural transition, enhances the electromigration of Ge along the [111] direction of FCC structure, which enables such a significant improvement. Set operation switches the amorphous to the (111)-oriented FCC structure.
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Affiliation(s)
- Chanyoung Yoo
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jeong Woo Jeon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seungjae Yoon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Yan Cheng
- Key Laboratory of Polar Materials and Devices, Department of Electronics, East China Normal University, Shanghai, 200241, China
| | - Gyuseung Han
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Wonho Choi
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Byongwoo Park
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gwangsik Jeon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sangmin Jeon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Woohyun Kim
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yonghui Zheng
- Key Laboratory of Polar Materials and Devices, Department of Electronics, East China Normal University, Shanghai, 200241, China
| | - Jongho Lee
- SK Hynix Inc., Icheon, Gyeonggi, 17336, Republic of Korea
| | - Junku Ahn
- SK Hynix Inc., Icheon, Gyeonggi, 17336, Republic of Korea
| | - Sunglae Cho
- SK Hynix Inc., Icheon, Gyeonggi, 17336, Republic of Korea
| | | | - Ilya V Karpov
- Components Research, Intel Corporation, Hillsboro, OR, 97124, USA
| | - Yoon Kyung Lee
- Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju, Jeonbuk, 54896, Republic of Korea
| | - Jung-Hae Choi
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Cheol Seong Hwang
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
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11
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Zewdie GM, Debela TT, Asres GA. Effect of temperature on structural, dynamical, and electronic properties of Sc 2Te 3 from first-principles calculations. RSC Adv 2022; 12:32796-32802. [PMID: 36425197 PMCID: PMC9665046 DOI: 10.1039/d2ra05720d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 11/03/2022] [Indexed: 09/08/2024] Open
Abstract
The compounds Sc2Te3 and Sb2Te3 have the same crystal structure. Ge-Sb-Te alloys are also the most common prototype phase change memory (PCM) compounds in the GeTe-Sb2Te3 pseudo-binary combination. Recently, alloying Sc atoms into Sb2Te3 has enabled sub-nanosecond switching in large conventional phase-change random access memory (PCRAM) devices. However, prior study on the electronic structure and dynamic properties of the Sc2Te3 system is very limited. In this work, we investigate the effect of temperature on the structural, dynamic, and electronic properties of the Sc2Te3 compound through ab initio molecular dynamics simulations. We show that the distorted-octahedral clusters are connected by four-fold rings even at higher temperatures. Moreover, our results clearly illustrate a liquid-to-glass transition temperature, which is between approximately 773 K and 950 K. The effect of temperature changes on the electronic properties of the system manifests as a metal-to-semiconductor transition. The band gap obtained using the mBJLDA functional is twice the value obtained using the PBE functional. Our studies provide useful insight into the local structure and dynamic and electronic properties of the Sc2Te3 system at the atomic level. We hope that this work could stimulate more theoretical work on the development of cache-type phase-change memory and broaden its application in the field of PCM.
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Affiliation(s)
- Getasew Mulualem Zewdie
- College of Mechanical and Industrial Engineering, Institute of Technology, Dire-Dawa University Dire-Dawa Ethiopia
| | - Tekalign Terfa Debela
- Institute for Application of Advanced Materials, Jeonju University Chonju Chonbuk 55069 Republic of Korea
| | - Georgies Alene Asres
- Center for Materials Engineering, Addis Ababa Institute of Technology, School of Multi-disciplinary Engineering Addis Ababa 1000 Ethiopia
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12
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Li S, Li M, Chen L, Xu X, Cui A, Zhou X, Jiang K, Shang L, Li Y, Zhang J, Zhu L, Hu Z, Chu J. Ultra-Stable, Endurable, and Flexible Sb 2Te xSe 3-x Phase Change Devices for Memory Application and Wearable Electronics. ACS APPLIED MATERIALS & INTERFACES 2022; 14:45600-45610. [PMID: 36178431 DOI: 10.1021/acsami.2c13792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Flexible memory and wearable electronics represent an emerging technology, thanks to their reliability, compatibility, and superior performance. Here, an Sb2TexSe3-x (STSe) phase change material was grown on flexible mica, which not only exhibited superior nature in thermal stability for phase change memory application but also revealed novel function performance in wearable electronics, thanks to its excellent mechanical reliability and endurance. The thermal stability of Sb2Te3 was improved obviously with the crystallization temperature elevated 60 K after Se doping, for the enhanced charge localization and stronger bonding energy, which was validated by the Vienna ab initio simulation package calculations. Based on the ultra-stability of STSe, the STSe-based phase change memory shows 65 000 reversible phase change ability. Moreover, the assembled flexible device can show real-time monitoring and recoverability response in sensing human activities in different parts of the body, which proves its effective reusability and potential as wearable electronics. Most importantly, the STSe device presents remarkable working reliability, reflected by excellent endurance over 100 s and long retention over 100 h. These results paved a novel way to utilize STSe phase change materials for flexible memory and wearable electronics with extreme thermal and mechanical stability and brilliant performance.
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Affiliation(s)
- Shubing Li
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Ming Li
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Li Chen
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Xionghu Xu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Anyang Cui
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Xin Zhou
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Kai Jiang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Liyan Shang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Yawei Li
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Jinzhong Zhang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Liangqing Zhu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Zhigao Hu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi, China
- Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
| | - Junhao Chu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Physics, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi, China
- Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
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13
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Zheng C, Simpson RE, Tang K, Ke Y, Nemati A, Zhang Q, Hu G, Lee C, Teng J, Yang JKW, Wu J, Qiu CW. Enabling Active Nanotechnologies by Phase Transition: From Electronics, Photonics to Thermotics. Chem Rev 2022; 122:15450-15500. [PMID: 35894820 DOI: 10.1021/acs.chemrev.2c00171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phase transitions can occur in certain materials such as transition metal oxides (TMOs) and chalcogenides when there is a change in external conditions such as temperature and pressure. Along with phase transitions in these phase change materials (PCMs) come dramatic contrasts in various physical properties, which can be engineered to manipulate electrons, photons, polaritons, and phonons at the nanoscale, offering new opportunities for reconfigurable, active nanodevices. In this review, we particularly discuss phase-transition-enabled active nanotechnologies in nonvolatile electrical memory, tunable metamaterials, and metasurfaces for manipulation of both free-space photons and in-plane polaritons, and multifunctional emissivity control in the infrared (IR) spectrum. The fundamentals of PCMs are first introduced to explain the origins and principles of phase transitions. Thereafter, we discuss multiphysical nanodevices for electronic, photonic, and thermal management, attesting to the broad applications and exciting promises of PCMs. Emerging trends and valuable applications in all-optical neuromorphic devices, thermal data storage, and encryption are outlined in the end.
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Affiliation(s)
- Chunqi Zheng
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore.,NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
| | - Robert E Simpson
- Engineering Product Development, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Kechao Tang
- Key Laboratory of Microelectronic Devices and Circuits (MOE), School of Integrated Circuits, Peking University, Beijing 100871, China
| | - Yujie Ke
- Engineering Product Development, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Arash Nemati
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Qing Zhang
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Guangwei Hu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Jinghua Teng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Joel K W Yang
- Engineering Product Development, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore.,Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Junqiao Wu
- Department of Materials Science and Engineering, University of California, Berkeley, and Lawrence Berkeley National Laboratory, California 94720, United States
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
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14
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Simultaneous emulation of synaptic and intrinsic plasticity using a memristive synapse. Nat Commun 2022; 13:2811. [PMID: 35589710 PMCID: PMC9120471 DOI: 10.1038/s41467-022-30432-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 04/25/2022] [Indexed: 12/02/2022] Open
Abstract
Neuromorphic computing targets the hardware embodiment of neural network, and device implementation of individual neuron and synapse has attracted considerable attention. The emulation of synaptic plasticity has shown promising results after the advent of memristors. However, neuronal intrinsic plasticity, which involves in learning process through interactions with synaptic plasticity, has been rarely demonstrated. Synaptic and intrinsic plasticity occur concomitantly in learning process, suggesting the need of the simultaneous implementation. Here, we report a neurosynaptic device that mimics synaptic and intrinsic plasticity concomitantly in a single cell. Threshold switch and phase change memory are merged in threshold switch-phase change memory device. Neuronal intrinsic plasticity is demonstrated based on bottom threshold switch layer, which resembles the modulation of firing frequency in biological neuron. Synaptic plasticity is also introduced through the nonvolatile switching of top phase change layer. Intrinsic and synaptic plasticity are simultaneously emulated in a single cell to establish the positive feedback between them. A positive feedback learning loop which mimics the retraining process in biological system is implemented in threshold switch-phase change memory array for accelerated training. Synaptic plasticity and neuronal intrinsic plasticity are both involved in the learning process of hardware artificial neural network. Here, Lee et al. integrate a threshold switch and a phase change memory in a single device, which emulates biological synaptic and intrinsic plasticity simultaneously.
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15
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Yang Z, Li B, Wang J, Wang X, Xu M, Tong H, Cheng X, Lu L, Jia C, Xu M, Miao X, Zhang W, Ma E. Designing Conductive-Bridge Phase-Change Memory to Enable Ultralow Programming Power. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2103478. [PMID: 35032111 PMCID: PMC8922100 DOI: 10.1002/advs.202103478] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/27/2021] [Indexed: 05/31/2023]
Abstract
Phase-change material (PCM) devices are one of the most mature nonvolatile memories. However, their high power consumption remains a bottleneck problem limiting the data storage density. One may drastically reduce the programming power by patterning the PCM volume down to nanometer scale, but that route incurs a stiff penalty from the tremendous cost associated with the complex nanofabrication protocols required. Instead, here a materials solution to resolve this dilemma is offered. The authors work with memory cells of conventional dimensions, but design/exploit a PCM alloy that decomposes into a heterogeneous network of nanoscale crystalline domains intermixed with amorphous ones. The idea is to confine the subsequent phase-change switching in the interface region of the crystalline nanodomain with its amorphous surrounding, forming/breaking "nano-bridges" that link up the crystalline domains into a conductive path. This conductive-bridge switching mechanism thus only involves nanometer-scale volume in programming, despite of the large areas in contact with the electrodes. The pore-like devices based on spontaneously phase-separated Ge13 Sb71 O16 alloy enable a record-low programming energy, down to a few tens of femtojoule. The new PCM/fabrication is fully compatible with the current 3D integration technology, adding no expenses or difficulty in processing.
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Affiliation(s)
- Zhe Yang
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Bowen Li
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Jiang‐Jing Wang
- Center for Alloy Innovation and Design (CAID)State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Xu‐Dong Wang
- Center for Alloy Innovation and Design (CAID)State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Meng Xu
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Hao Tong
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Xiaomin Cheng
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Lu Lu
- The School of MicroelectronicsState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Chunlin Jia
- The School of MicroelectronicsState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - Ming Xu
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Xiangshui Miao
- Wuhan National Laboratory for OptoelectronicsSchool of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan430074China
| | - Wei Zhang
- Center for Alloy Innovation and Design (CAID)State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
| | - En Ma
- Center for Alloy Innovation and Design (CAID)State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China
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16
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Rules of hierarchical melt and coordinate bond to design crystallization in doped phase change materials. Nat Commun 2021; 12:6473. [PMID: 34753920 PMCID: PMC8578292 DOI: 10.1038/s41467-021-26696-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 09/27/2021] [Indexed: 11/23/2022] Open
Abstract
While alloy design has practically shown an efficient strategy to mediate two seemingly conflicted performances of writing speed and data retention in phase-change memory, the detailed kinetic pathway of alloy-tuned crystallization is still unclear. Here, we propose hierarchical melt and coordinate bond strategies to solve them, where the former stabilizes a medium-range crystal-like region and the latter provides a rule to stabilize amorphous. The Er0.52Sb2Te3 compound we designed achieves writing speed of 3.2 ns and ten-year data retention of 161 °C. We provide a direct atomic-level evidence that two neighbor Er atoms stabilize a medium-range crystal-like region, acting as a precursor to accelerate crystallization; meanwhile, the stabilized amorphous originates from the formation of coordinate bonds by sharing lone-pair electrons of chalcogenide atoms with the empty 5d orbitals of Er atoms. The two rules pave the way for the development of storage-class memory with comprehensive performance to achieve next technological node. In phase-change memory, writing speed and data retention are two seemingly conflicting performances. Here the authors report hierarchical melt and coordinate bond strategies to stabilize a medium-range crystal-like region and amorphous region, respectively.
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17
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Han JH, Jeong H, Park H, Kwon H, Kim D, Lim D, Baik SJ, Kwon YK, Cho MH. Enhanced reliability of phase-change memory via modulation of local structure and chemical bonding by incorporating carbon in Ge 2Sb 2Te 5. RSC Adv 2021; 11:22479-22488. [PMID: 35480803 PMCID: PMC9034215 DOI: 10.1039/d1ra02210e] [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: 03/19/2021] [Accepted: 06/21/2021] [Indexed: 12/22/2022] Open
Abstract
In this study, we investigated the effect of phase-change characteristics on the device performance of carbon-incorporated Ge2Sb2Te5 (CGST) to understand the origin of the enhanced reliability and stabilization of the device. Macroscopic and microscopic measurements confirmed that the structural stability significantly increased with the incorporation of as much as 10% carbon. After the completion of bond formation between C and Ge, the excess C (>5 atomic%) engages in bonding with Sb in localized regions because of the difference in formation energy. These bonds of C with Ge and Sb induce non-uniform local charge density of the short-range order. Finally, because the strong bonds between Ge and C shorten the short Ge-Te bonds, the high thermal stability of CGST relative to that of GST can be attributed to intensified Peierls distortion. The formation of strong bonds successfully underpins the local structures and reduces the stochastic effect. Moreover, extension of the C bonding to Sb enhances the structural reliability, resulting in highly stable CGST in the amorphous phase. Finally, the device stability of CGST in the reset state of the amorphous structure during the device switching process was significantly improved.
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Affiliation(s)
- Jeong Hwa Han
- Department of Physics, Yonsei University Seoul 03722 Republic of Korea
| | - Hun Jeong
- Department of Physics, Yonsei University Seoul 03722 Republic of Korea
| | - Hanjin Park
- Department of Physics, Research Institute for Basic Sciences, Kyung Hee University Seoul 02447 Republic of Korea
| | - Hoedon Kwon
- Department of Physics, Yonsei University Seoul 03722 Republic of Korea
| | - Dasol Kim
- Department of Physics, Yonsei University Seoul 03722 Republic of Korea
| | - Donghyeok Lim
- Department of Materials Science and Engineering, UNIST Ulsan 44919 Republic of Korea
| | - Seung Jae Baik
- Faculty of Electronic and Electrical Engineering, Hankyong National University Anseong 17579 Republic of Korea
| | - Young-Kyun Kwon
- Department of Physics, Research Institute for Basic Sciences, Kyung Hee University Seoul 02447 Republic of Korea .,Department of Information Display, Kyung Hee University Seoul 02447 Republic of Korea
| | - Mann-Ho Cho
- Department of Physics, Yonsei University Seoul 03722 Republic of Korea .,Department of System Semiconductor Engineering, Yonsei University Seoul 03722 Republic of Korea
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18
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On-the-fly closed-loop materials discovery via Bayesian active learning. Nat Commun 2020; 11:5966. [PMID: 33235197 PMCID: PMC7686338 DOI: 10.1038/s41467-020-19597-w] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/13/2020] [Indexed: 11/08/2022] Open
Abstract
Active learning—the field of machine learning (ML) dedicated to optimal experiment design—has played a part in science as far back as the 18th century when Laplace used it to guide his discovery of celestial mechanics. In this work, we focus a closed-loop, active learning-driven autonomous system on another major challenge, the discovery of advanced materials against the exceedingly complex synthesis-processes-structure-property landscape. We demonstrate an autonomous materials discovery methodology for functional inorganic compounds which allow scientists to fail smarter, learn faster, and spend less resources in their studies, while simultaneously improving trust in scientific results and machine learning tools. This robot science enables science-over-the-network, reducing the economic impact of scientists being physically separated from their labs. The real-time closed-loop, autonomous system for materials exploration and optimization (CAMEO) is implemented at the synchrotron beamline to accelerate the interconnected tasks of phase mapping and property optimization, with each cycle taking seconds to minutes. We also demonstrate an embodiment of human-machine interaction, where human-in-the-loop is called to play a contributing role within each cycle. This work has resulted in the discovery of a novel epitaxial nanocomposite phase-change memory material. Machine learning driven research holds big promise towards accelerating materials’ discovery. Here the authors demonstrate CAMEO, which integrates active learning Bayesian optimization with practical experiments execution, for the discovery of new phase- change materials using X-ray diffraction experiments.
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19
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Hwang S, Park H, Kim D, Lim H, Lee C, Han JH, Kwon YK, Cho MH. Ultra-low Energy Phase Change Memory with Improved Thermal Stability by Tailoring the Local Structure through Ag Doping. ACS APPLIED MATERIALS & INTERFACES 2020; 12:37285-37294. [PMID: 32697074 DOI: 10.1021/acsami.0c05811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Although Sb2Te3, as a candidate material for next-generation memory devices, has attractive properties such as higher operation speed and lower power consumption than Ge2Sb2Te5, its poor stability prevents its application to commercial memory devices. Transition metal dopants provide enhancements in its phase change characteristics, improving both thermal stability and operation energy. However, the enhancement mechanism remains to be sufficiently investigated, and standard properties need to be achieved. Herein, the phase change properties of Sb2Te3 are confirmed to be enhanced by the incorporation of a heavy transition metal element such as Ag. The crystallization temperature increases by nearly 40%, and the operation energy is reduced by approximately 60%. These enhancements are associated with the changes in the local Sb2Te3 structure caused by Ag incorporation. As the incorporated Ag atoms substitute Sb in the Sb-Te octahedron, this turns into a Ag-Te defective tetrahedron with a strong Ag-Te bond that induces distortion in the crystal lattice. The formation of this bond is attributed to the electron configuration of Ag and its fully filled d orbital. Thus, Ag-doped Sb2Te3 is a promising candidate for practical phase change memory devices with high stability and high operation speed.
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Affiliation(s)
- Soobin Hwang
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Atomic Scale Surface Science Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Hanjin Park
- Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Dasol Kim
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Atomic Scale Surface Science Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Hyeonwook Lim
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Atomic Scale Surface Science Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Changwoo Lee
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Atomic Scale Surface Science Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Jeong Hwa Han
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Atomic Scale Surface Science Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Young-Kyun Kwon
- Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Mann-Ho Cho
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Atomic Scale Surface Science Center, Yonsei University, Seoul 03722, Republic of Korea
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20
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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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Behrens M, Lotnyk A, Bryja H, Gerlach JW, Rauschenbach B. Structural Transitions in Ge 2Sb 2Te 5 Phase Change Memory Thin Films Induced by Nanosecond UV Optical Pulses. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E2082. [PMID: 32369916 PMCID: PMC7254329 DOI: 10.3390/ma13092082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/26/2020] [Accepted: 04/28/2020] [Indexed: 11/16/2022]
Abstract
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.
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Affiliation(s)
- Mario Behrens
- Department of Precision Surfaces, Leibniz Institute of Surface Engineering (IOM), Permoserstr 15, 04318 Leipzig, Germany; (H.B.); (J.W.G.); (B.R.)
| | - Andriy Lotnyk
- Department of Precision Surfaces, Leibniz Institute of Surface Engineering (IOM), Permoserstr 15, 04318 Leipzig, Germany; (H.B.); (J.W.G.); (B.R.)
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies, Ningbo University, Ningbo 315211, China
| | - Hagen Bryja
- Department of Precision Surfaces, Leibniz Institute of Surface Engineering (IOM), Permoserstr 15, 04318 Leipzig, Germany; (H.B.); (J.W.G.); (B.R.)
| | - Jürgen W. Gerlach
- Department of Precision Surfaces, Leibniz Institute of Surface Engineering (IOM), Permoserstr 15, 04318 Leipzig, Germany; (H.B.); (J.W.G.); (B.R.)
| | - Bernd Rauschenbach
- Department of Precision Surfaces, Leibniz Institute of Surface Engineering (IOM), Permoserstr 15, 04318 Leipzig, Germany; (H.B.); (J.W.G.); (B.R.)
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Behrens M, Lotnyk A, Gerlach JW, Ehrhardt M, Lorenz P, Rauschenbach B. Direct Measurement of Crystal Growth Velocity in Epitaxial Phase-Change Material Thin Films. ACS APPLIED MATERIALS & INTERFACES 2019; 11:41544-41550. [PMID: 31612702 DOI: 10.1021/acsami.9b16111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Central to the use of Ge-Sb-Te based phase-change materials for data storage applications is their crystallization capability since it determines memory writing time. Although being intensively studied to identify intrinsic limits and develop strategies to enhance memory performance, the crystallization process in these materials is still not fully explored. Therefore, this study focuses on the determination of crystal growth dynamics in an epitaxial phase-change material thin film model system offering the advantage of high crystalline quality and application-relevant sizing. By introducing a method that combines time-resolved reflectivity measurements with high-resolution scanning transmission electron microscopy, crystal growth velocities upon fast cooling after single ns-laser pulse irradiation of the prototypical phase-change material Ge2Sb2Te5 are determined. As a result, an increase in crystal growth velocity from 0.4 to 1.7 m/s with increasing laser fluence is observed with a maximum rate of 1.7 m/s as the upper detectable limit of the studied material.
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Affiliation(s)
- Mario Behrens
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
| | - Andriy Lotnyk
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
| | - Jürgen W Gerlach
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
| | - Martin Ehrhardt
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
| | - Pierre Lorenz
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
| | - Bernd Rauschenbach
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
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23
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Direct atomic insight into the role of dopants in phase-change materials. Nat Commun 2019; 10:3525. [PMID: 31388013 PMCID: PMC6684653 DOI: 10.1038/s41467-019-11506-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 07/15/2019] [Indexed: 11/09/2022] Open
Abstract
Doping is indispensable to tailor phase-change materials (PCM) in optical and electronic data storage. Very few experimental studies, however, have provided quantitative information on the distribution of dopants on the atomic-scale. Here, we present atom-resolved images of Ag and In dopants in Sb2Te-based (AIST) PCM using electron microscopy and atom-probe tomography. Combing these with DFT calculations and chemical-bonding analysis, we unambiguously determine the dopants’ role upon recrystallization. Composition profiles corroborate the substitution of Sb by In and Ag, and the segregation of excessive Ag into grain boundaries. While In is bonded covalently to neighboring Te, Ag binds ionically. Moreover, In doping accelerates the crystallization and hence operation while Ag doping limits the random diffusion of In atoms and enhances the thermal stability of the amorphous phase. Quantitative imaging on the doping in phase-change materials for data storage remains scarce. Here, the authors combine electron microscopy, atom probe tomography, and simulations to determine the role of indium and silver dopants during recrystallization.
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Wang Y, Guo T, Liu G, Li T, Lv S, Song S, Cheng Y, Song W, Ren K, Song Z. Sc-Centered Octahedron Enables High-Speed Phase Change Memory with Improved Data Retention and Reduced Power Consumption. ACS APPLIED MATERIALS & INTERFACES 2019; 11:10848-10855. [PMID: 30810295 DOI: 10.1021/acsami.8b22580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Phase change memory (PCM) with advantages of high operation speed, multilevel storage capability, spiking-time-dependent plasticity, etc., has wide application scenarios in both Von Neumann systems and neuromorphic systems. In the automotive application, intelligent system not only needs high efficiency to handle massive data processing but also good robustness to retain the existing data against high working temperature. In this work, Sc-doped GeTe is developed for PCM, which has achieved 120 °C data retention for 10 years, 6 ns operation speed, and 7 nJ low power consumption. The high data retention is attributed to the high coordination number of Sc and its strong bonds with Te atoms in the amorphous phase, which enhances the robustness of the atomic matrices. Sc-centered octahedrons in amorphous state provide a nucleation center, leading to fast crystallization. In the crystalline phase, Sc atoms occupy Ge vacancies to form a homogenous GeTe-like rhombohedral phase. The strong covalent-like Sc-Te bonds weaken the neighboring Ge-Te bonds, lowering energy for melting. Together with the increased energy efficiency originated from confined grain size, the reduced power consumption has been achieved. The improvements in data retention, speed, and power efficiency have made Sc-doped GeTe a promising candidate for high-performance automobile electronics application.
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Affiliation(s)
- Yong Wang
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Tianqi Guo
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Guangyu Liu
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Tao Li
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Shilong Lv
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
| | - Sannian Song
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
| | - Yan Cheng
- Key Laboratory of Polar Materials and Devices, Ministry of Education , East China Normal University , Shanghai 200062 , China
| | - Wenxiong Song
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , 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, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
- College of Materials and Environmental Engineering , Hangzhou Dianzi University , Hangzhou , Zhejiang 310018 , China
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology , Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences , Shanghai 200050 , China
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Shen J, Lv S, Chen X, Li T, Zhang S, Song Z, Zhu M. Thermal Barrier Phase Change Memory. ACS APPLIED MATERIALS & INTERFACES 2019; 11:5336-5343. [PMID: 30624043 DOI: 10.1021/acsami.8b18473] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Phase change memory is widely considered as the most promising candidate as storage class memory (SCM), bridging the performance gaps between dynamic random access memory and flash. However, high required operation current remains the major limitation for the SCM application, even after using defect engineering materials, for example, Ti-doped Sb2Te3. Here, we demonstrate that ∼87% current can be reduced by spatially separating Sb2Te3 and TiTe2 layers, thanks to semimetallic TiTe2 serving as a thermal barrier in the reset process. Moreover, the stable crystalline TiTe2 layer provides an ordered interface to speed up the crystallization process of the amorphous Sb2Te3 layer, enabling ∼10 ns ultrafast crystallization speed. An outstanding device lifetime, up to ∼2 × 107 cycles, has been obtained, which is twice as long as that of alloy-based cells. Correlative electron microscopy and atom probe tomography provide evidence that the TiTe2/Sb2Te3 multilayer can keep a layer-stacked structure, avoiding phase segregation found in alloys and strong element intermixing in the GeTe/Sb2Te3 superlattice, which enables excellent cyclability. This study suggests that adding a semimetallic layer in the phase change layer, such as TiTe2 and TiSe2, can yield a phase change memory with superior properties.
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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 , China
- University of the Chinese Academy of Sciences , Beijing 100080 , People's Republic of China
| | - Shilong Lv
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology , Chinese Academy of Sciences , Shanghai 200050 , China
| | - 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 , Shanghai Tech University , Shanghai 201210 , 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
- University of the Chinese Academy of Sciences , Beijing 100080 , People's Republic of China
| | - Sifan Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology , Chinese Academy of Sciences , Shanghai 200050 , China
- University of the Chinese Academy of Sciences , Beijing 100080 , People's Republic of 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
| | - 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
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26
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Ren K, Zhu M, Song W, Lv S, Xia M, Wang Y, Lu Y, Ji Z, Song Z. Electrical switching properties and structural characteristics of GeSe-GeTe films. NANOSCALE 2019; 11:1595-1603. [PMID: 30475356 DOI: 10.1039/c8nr07832g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Germanium chalcogenides, especially GeSe and GeTe alloys, have recently gained popularity because of their Ovonic threshold (volatile) and memory (non-volatile) switching properties, with great potential for electric storage applications. Materials designed in a pseudo-binary way may possess superior properties in their phase transition, e.g. GeTe-Sb2Te3 materials, and bring about revolutionary advances in optical storage. However, to date, the electrical switching behaviors of films of pseudo-binary GeSe-GeTe have not yet been studied, and neither have the structural characteristics. Herein, we present both the thermally and electrically induced switching behaviors of GeSe-GeTe film, as well as the structural evolution due to composition tuning. The crystallization temperature of GeSe-GeTe films increases with GeSe content quite sensitively. An atom-resolved picture of the GeSe-GeTe alloy with a state-of-the-art atomic mapping technology has been presented, where a randomly mixed arrangement of Se and Te atoms is determined unambiguously in Ge50Se13Te34 with a GeTe-like rhombohedral structure. The local structural motifs in GeSe-GeTe, more specifically, sixfold coordinated octahedra with a distinguished degree of Peierls distortion and geometric variety, are essential to understand its electric properties. GeSe-GeTe alloy, Ge50Se13Te34, based memory cells have been fabricated, showing a fast memory switching behavior and excellent retention of 10 years at 208 °C.
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Affiliation(s)
- Kun Ren
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
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27
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Wang G, Lotnyk A, Nie Q, Wang R, Shen X, Lu Y. Shortening Nucleation Time to Enable Ultrafast Phase Transition in Zn 1Sb 7Te 12 Pseudo-Binary Alloy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:15143-15149. [PMID: 30449104 DOI: 10.1021/acs.langmuir.8b02737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Zn1Sb7Te12 thin films have been deposited by magnetron co-sputtering of ZnTe and Sb2Te3 targets. The microstructure, phase-change speed, optical cycling stability, and crystallization kinetics have been investigated during thermal annealing and laser irradiation. The thermal-annealed and laser-irradiated films give a clear evidence of the coexistence of trigonal Sb2Te3 and cubic ZnTe phases, which are homogeneously distributed in a single alloy as confirmed by advanced scanning transmission electron microscopy. The formation of both phases increases the initial nucleation sites, leading to the rapid phase-change speed in the Zn1Sb7Te12 film. The film has a minimum crystallization time of ∼3 ns at 70 mW with almost no incubation period for the formation of critical nuclei compared to Ge2Sb2Te5 and other Zn-based films. Moreover, the complete crystallization of Zn1Sb7Te12 thin films is achieved within 10 ns. The ultrafast two-dimensional nucleation and crystal growth speed in Zn1Sb7Te12 obtained from the laser-irradiated system is almost 7 times faster compared to that in Ge2Sb2Te5 film. Controlling the crystallization process through doping ZnTe into Sb2Te3 is thus promising for the development of high-speed optical switching technology.
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Affiliation(s)
- Guoxiang Wang
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies , Ningbo University , Ningbo , Zhejiang 315211 , China
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
- Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province , Ningbo , Zhejiang 315211 , China
| | - Andriy Lotnyk
- Leibniz Institute of Surface Engineering (IOM) , Permoserstr. 15 , D-04318 Leipzig , Germany
| | - Qiuhua Nie
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies , Ningbo University , Ningbo , Zhejiang 315211 , China
- Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province , Ningbo , Zhejiang 315211 , China
| | - Rongping Wang
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies , Ningbo University , Ningbo , Zhejiang 315211 , China
- Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province , Ningbo , Zhejiang 315211 , China
| | - Xiang Shen
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies , Ningbo University , Ningbo , Zhejiang 315211 , China
- Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province , Ningbo , Zhejiang 315211 , China
| | - Yegang Lu
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies , Ningbo University , Ningbo , Zhejiang 315211 , China
- Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province , Ningbo , Zhejiang 315211 , China
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28
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Guo T, Song S, Zheng Y, Xue Y, Yan S, Liu Y, Li T, Liu G, Wang Y, Song Z, Qi M, Feng S. Excellent thermal stability owing to Ge and C doping in Sb 2Te-based high-speed phase-change memory. NANOTECHNOLOGY 2018; 29:505710. [PMID: 30264733 DOI: 10.1088/1361-6528/aae4f4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The contradictory nature between transition speed and thermal stability of phase-change materials has always been the key limitation to the achievement of wide applications under harsh conditions. Ge2.3Sb2.0Te phase-change alloy is proposed here to feature high thermal stability (10 year data retention above 220 °C) and fast switching speed (SET programming speed up to 5 ns) for electronic storage. In mushroom-shaped device cells, the nanocomposite materials implement an endurance life of nearly 1 × 105 cycles. Such operation speed among high-temperature alloys is the best ever reported. And the moderate incorporation of C offers intriguing benefits that include enhanced thermal stability and reduced RESET voltage in the above-mentioned Ge-rich Sb2Te-based memory cells. Through microscopic analysis, the local segregation of C dopants can further refine the crystalline grains and thus induce a lower volume change and roughness upon heating. These properties are crucial with regard to the application potential in high-performance and high-density embedded memories.
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Affiliation(s)
- Tianqi Guo
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China. Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China. University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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29
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Zhu W, Yang R, Fan Y, Fu Q, Wu H, Zhang P, Shen NH, Zhang F. Controlling optical polarization conversion with Ge 2Sb 2Te 5-based phase-change dielectric metamaterials. NANOSCALE 2018; 10:12054-12061. [PMID: 29911240 DOI: 10.1039/c8nr02587h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recent progress in the metamaterial-based polarization manipulation of light highlights the promise of novel polarization-dependent optical components and systems. To overcome the limited frequency bandwidth of metamaterials resulting from their resonant nature, it is desirable to incorporate tunability into metamaterial-based polarization manipulations. Here, we propose a dielectric metamaterial for controlling linear polarization conversion using the phase-change characteristic of Ge2Sb2Te5 (GST), whose refractive index changes significantly when transforming from the amorphous phase to the crystalline phase under external stimuli. The polarization conversion phenomena are systematically studied using different arrangements of GST in this metamaterial. The performance of linear polarization conversion and the tunability are also analyzed and compared in three different designs. It is found that phase-change materials such as GST can be employed in dielectric materials for tunable and switchable linear polarization conversion in the telecom band. The conversion efficiency can be significantly modulated during the phase transition. Our results provide useful insights for incorporating phase-change materials with metamaterials for tunable polarization manipulation.
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Affiliation(s)
- Wei Zhu
- Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Department of Applied Physics, School of Science, Northwestern Polytechnical University, Xi'an 710129, China.
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30
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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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31
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Su Y, Wang XD, Yu Q, Cao QP, Ruett U, Zhang DX, Jiang JZ. Temperature dependent structural evolution in liquid Ag 50Ga 50 alloy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:015402. [PMID: 29185998 DOI: 10.1088/1361-648x/aa996c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The temperature dependence of atomic structural evolution in liquid Ag50Ga50 alloy has been studied using an in situ high energy x-ray diffraction (XRD) experiment combined with first-principles molecular dynamics (FPMD) simulations. The experimental data show a reversible structural crossover at the temperature of about 1050 K. Changes in both electrical resistivity and absolute thermoelectric power at about 1100 K strongly support the XRD results. Additionally, FPMD simulations reveal the abnormal temperature dependent behavior of partial coordination number and atomic diffusivity at about 1200 K, elucidating that the partition experimentally observed changes in structure and properties could be linked with the repartition between Ag and Ga atoms in the liquid at around 1050-1200 K. This finding will trigger more studies on the structural evolution of noble-polyvalent metals in particular and metallic liquids in general.
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Affiliation(s)
- Y Su
- International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China
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32
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Rao F, Ding K, Zhou Y, Zheng Y, Xia M, Lv S, Song Z, Feng S, Ronneberger I, Mazzarello R, Zhang W, Ma E. Reducing the stochasticity of crystal nucleation to enable subnanosecond memory writing. Science 2017; 358:1423-1427. [PMID: 29123020 DOI: 10.1126/science.aao3212] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/30/2017] [Indexed: 01/26/2023]
Abstract
Operation speed is a key challenge in phase-change random-access memory (PCRAM) technology, especially for achieving subnanosecond high-speed cache memory. Commercialized PCRAM products are limited by the tens of nanoseconds writing speed, originating from the stochastic crystal nucleation during the crystallization of amorphous germanium antimony telluride (Ge2Sb2Te5). Here, we demonstrate an alloying strategy to speed up the crystallization kinetics. The scandium antimony telluride (Sc0.2Sb2Te3) compound that we designed allows a writing speed of only 700 picoseconds without preprogramming in a large conventional PCRAM device. This ultrafast crystallization stems from the reduced stochasticity of nucleation through geometrically matched and robust scandium telluride (ScTe) chemical bonds that stabilize crystal precursors in the amorphous state. Controlling nucleation through alloy design paves the way for the development of cache-type PCRAM technology to boost the working efficiency of computing systems.
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Affiliation(s)
- Feng Rao
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.,College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Keyuan Ding
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.,College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yuxing Zhou
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, 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
| | - Mengjiao Xia
- International Laboratory of Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Shilong Lv
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, 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.
| | - Songlin Feng
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Ider Ronneberger
- Institute for Theoretical Solid State Physics, JARA-FIT and JARA-HPC, RWTH Aachen University, Aachen D-52074, Germany
| | - Riccardo Mazzarello
- Institute for Theoretical Solid State Physics, JARA-FIT and JARA-HPC, RWTH Aachen University, Aachen D-52074, Germany
| | - Wei Zhang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
| | - Evan Ma
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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Liu R, Zhou X, Zhai J, Song J, Wu P, Lai T, Song S, Song Z. Multilayer SnSb 4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability. ACS APPLIED MATERIALS & INTERFACES 2017; 9:27004-27013. [PMID: 28737032 DOI: 10.1021/acsami.7b06533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb4-SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb2Se3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb4-SbSe thin film.
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Affiliation(s)
- Ruirui Liu
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, School of Materials Science & Engineering, Tongji University , Shanghai 201804, China
- Department of Mining and Materials Engineering, McGill University , Montreal, Quebec H3A 0C5, Canada
| | - Xiao Zhou
- Department of Mining and Materials Engineering, McGill University , Montreal, Quebec H3A 0C5, Canada
| | - Jiwei Zhai
- Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, School of Materials Science & Engineering, Tongji University , Shanghai 201804, China
| | - Jun Song
- Department of Mining and Materials Engineering, McGill University , Montreal, Quebec H3A 0C5, Canada
| | - Pengzhi Wu
- Department of Physics, State Key Laboratory of Optoelectronic Materials and Technology, Sun Yat-Sen University , Guangzhou 510275, China
| | - Tianshu Lai
- Department of Physics, State Key Laboratory of Optoelectronic Materials and Technology, Sun Yat-Sen University , Guangzhou 510275, 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
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences , Shanghai 200050, China
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Wang JJ, Xu YZ, Mazzarello R, Wuttig M, Zhang W. A Review on Disorder-Driven Metal-Insulator Transition in Crystalline Vacancy-Rich GeSbTe Phase-Change Materials. MATERIALS 2017; 10:ma10080862. [PMID: 28773222 PMCID: PMC5578228 DOI: 10.3390/ma10080862] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/23/2017] [Accepted: 07/25/2017] [Indexed: 12/14/2022]
Abstract
Metal-insulator transition (MIT) is one of the most essential topics in condensed matter physics and materials science. The accompanied drastic change in electrical resistance can be exploited in electronic devices, such as data storage and memory technology. It is generally accepted that the underlying mechanism of most MITs is an interplay of electron correlation effects (Mott type) and disorder effects (Anderson type), and to disentangle the two effects is difficult. Recent progress on the crystalline Ge₁Sb₂Te₄ (GST) compound provides compelling evidence for a disorder-driven MIT. In this work, we discuss the presence of strong disorder in GST, and elucidate its effects on electron localization and transport properties. We also show how the degree of disorder in GST can be reduced via thermal annealing, triggering a disorder-driven metal-insulator transition. The resistance switching by disorder tuning in crystalline GST may enable novel multilevel data storage devices.
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Affiliation(s)
- Jiang-Jing Wang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Ya-Zhi Xu
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Riccardo Mazzarello
- Institute for Theoretical Solid-State Physics, JARA-FIT and JARA-HPC, RWTH Aachen University, 52074 Aachen, Germany.
| | - Matthias Wuttig
- Institute of Physics IA, JARA-FIT and JARA-HPC, RWTH Aachen University, 52074 Aachen, Germany.
| | - Wei Zhang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
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35
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Surface Energy Driven Cubic-to-Hexagonal Grain Growth of Ge 2Sb 2Te 5 Thin Film. Sci Rep 2017; 7:5915. [PMID: 28725023 PMCID: PMC5517630 DOI: 10.1038/s41598-017-06426-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 06/12/2017] [Indexed: 11/23/2022] Open
Abstract
Phase change memory (PCM) is a promising nonvolatile memory to reform current commercial computing system. Inhibiting face-centered cubic (f-) to hexagonal (h-) phase transition of Ge2Sb2Te5 (GST) thin film is essential for realizing high-density, high-speed, and low-power PCM. Although the atomic configurations of f- and h-lattices of GST alloy and the transition mechanisms have been extensively studied, the real transition process should be more complex than previous explanations, e.g. vacancy-ordering model for f-to-h transition. In this study, dynamic crystallization procedure of GST thin film was directly characterized by in situ heating transmission electron microscopy. We reveal that the equilibrium to h-phase is more like an abnormal grain growth process driven by surface energy anisotropy. More specifically, [0001]-oriented h-grains with the lowest surface energy grow much faster by consuming surrounding small grains, no matter what the crystallographic reconfigurations would be on the frontier grain-growth boundaries. We argue the widely accepted vacancy-ordering mechanism may not be indispensable for the large-scale f-to-h grain growth procedure. The real-time observations in this work contribute to a more comprehensive understanding of the crystallization behavior of GST thin film and can be essential for guiding its optimization to achieve high-performance PCM applications.
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36
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Dependence of Solidification for Bi 2Te 3-xSe x Alloys on Their Liquid States. Sci Rep 2017; 7:2463. [PMID: 28550312 PMCID: PMC5446403 DOI: 10.1038/s41598-017-02507-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 04/12/2017] [Indexed: 11/29/2022] Open
Abstract
The resistivity versus temperature (ρ-T) behaviours of liquid n-type Bi2Te3−xSex (x = 0.3, 0.45 and 0.6) alloys are explored up to 1050 °C. A clear hump is observed on all ρ-T curves of the three studied Bi2Te3−xSex melts during the heating process, which suggests that a temperature-induced liquid-liquid structural transition takes place in the melts. Based on this information, the solidification behaviours and microstructures of the alloys with different liquid states are investigated. The samples that experienced liquid structural transition show that the nucleation and growth undercooling degrees are conspicuously enlarged and the solidification time is shortened. As a result, the solidified lamellae are refined and homogenized, the prevalence of low-angle grain boundaries between these lamellae is increased, and the Vicker Hardness is enhanced. Atom probe tomography analyses prove that there is no segregation or nanoprecipitation within the grains, but the Te-rich eutectic structure and the evolution of composition near the Te-matrix phase boundary are investigated in a sample that experienced liquid structural transition. Our work implies that the solidification behaviours of Bi2Te3−xSex alloys are strongly related to their parent liquid states, providing an alternative approach to tailor the thermoelectric and mechanical properties even when only a simple solidification process is performed.
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37
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Lu Y, Stegmaier M, Nukala P, Giambra MA, Ferrari S, Busacca A, Pernice WHP, Agarwal R. Mixed-Mode Operation of Hybrid Phase-Change Nanophotonic Circuits. NANO LETTERS 2017; 17:150-155. [PMID: 27959556 DOI: 10.1021/acs.nanolett.6b03688] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Phase change materials (PCMs) are highly attractive for nonvolatile electrical and all-optical memory applications because of unique features such as ultrafast and reversible phase transitions, long-term endurance, and high scalability to nanoscale dimensions. Understanding their transient characteristics upon phase transition in both the electrical and the optical domains is essential for using PCMs in future multifunctional optoelectronic circuits. Here, we use a PCM nanowire embedded into a nanophotonic circuit to study switching dynamics in mixed-mode operation. Evanescent coupling between light traveling along waveguides and a phase-change nanowire enables reversible phase transition between amorphous and crystalline states. We perform time-resolved measurements of the transient change in both the optical transmission and resistance of the nanowire and show reversible switching operations in both the optical and the electrical domains. Our results pave the way toward on-chip multifunctional optoelectronic integrated devices, waveguide integrated memories, and hybrid processing applications.
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Affiliation(s)
- Yegang Lu
- Faculty of Electrical Engineering and Computer Science, Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province, Ningbo University , Zhejiang, 315211, China
| | | | - Pavan Nukala
- Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Marco A Giambra
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen 76344, Germany
- Università degli Studi di Palermo , 90133 Palermo, Italy
| | - Simone Ferrari
- Institute of Physics, University of Muenster , Muenster 48149, Germany
| | | | | | - Ritesh Agarwal
- Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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38
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Li Z, Si C, Zhou J, Xu H, Sun Z. Yttrium-Doped Sb 2Te 3: A Promising Material for Phase-Change Memory. ACS APPLIED MATERIALS & INTERFACES 2016; 8:26126-26134. [PMID: 27612285 DOI: 10.1021/acsami.6b08700] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Sb2Te3 exhibits outstanding performance among the candidate materials for phase-change memory; nevertheless, its low electrical resistivity and thermal stability hinder its practical application. Hence, numerous studies have been carried out to search suitable dopants to improve the performance; however, the explored dopants always cause phase separation and thus drastically reduce the reliability of phase-change memory. In this work, on the basis of ab initio calculations, we have identified yttrium (Y) as an optimal dopant for Sb2Te3, which overcomes the phase separation problem and significantly increases the resistivity of crystalline state by at least double that of Sb2Te3. The good phase stability of crystalline Y-doped Sb2Te3 (YST) is attributed to the same crystal structure between Y2Te3 and Sb2Te3 as well as their tiny lattice mismatch of only ∼1.1%. The significant increase in resistivity of c-YST is understood by our findings that Y can dramatically increase the carrier's effective mass by regulating the band structure and can also reduce the intrinsic carrier density by suppressing the formation of SbTe antisite defects. Y doping can also improve the thermal stability of amorphous YST based on our ab initio molecular dynamics simulations, which is attributed to the stronger interactions between Y and Te than that of Sb and Te.
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Affiliation(s)
- 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
| | - Chen Si
- School of Materials Science and Engineering and ‡Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University , Beijing 100191, 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
| | - Huibin Xu
- School of Materials Science and Engineering and ‡Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University , Beijing 100191, 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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39
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Low-Energy Amorphization of Ti1Sb2Te5 Phase Change Alloy Induced by TiTe2 Nano-Lamellae. Sci Rep 2016; 6:30645. [PMID: 27469931 PMCID: PMC4965780 DOI: 10.1038/srep30645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/08/2016] [Indexed: 11/08/2022] Open
Abstract
Increasing SET operation speed and reducing RESET operation energy have always been the innovation direction of phase change memory (PCM) technology. Here, we demonstrate that ∼87% and ∼42% reductions of RESET operation energy can be achieved on PCM cell based on stoichiometric Ti1Sb2Te5 alloy, compared with Ge2Sb2Te5 and non-stoichiometric Ti0.4Sb2Te3 based PCM cells at the same size, respectively. The Ti1Sb2Te5 based PCM cell also shows one order of magnitude faster SET operation speed compared to that of the Ge2Sb2Te5 based one. The enhancements may be caused by substantially increased concentration of TiTe2 nano-lamellae in crystalline Ti1Sb2Te5 phase. The highly electrical conduction and lowly thermal dissipation of the TiTe2 nano-lamellae play a major role in enhancing the thermal efficiency of the amorphization, prompting the low-energy RESET operation. Our work may inspire the interests to more thorough understanding and tailoring of the nature of the (TiTe2)n(Sb2Te3)m pseudobinary system which will be advantageous to realize high-speed and low-energy PCM applications.
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40
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Du J, Wang M, Chen N, Xie S, Yu H, Wu Q. Instability origin and improvement scheme of facial Alq3 for blue OLED application. Chem Res Chin Univ 2016. [DOI: 10.1007/s40242-016-5485-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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41
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Sun Y, Wang X, Du J, Chen N, Yu H, Wu Q, Meng X. Amorphous structure and bonding chemistry of aluminium antimonide(AlSb)) alloy for phase-change memory device. Chem Res Chin Univ 2016. [DOI: 10.1007/s40242-016-5345-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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42
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Chen L, Song S, Song Z, Li L, Zhang X, Zheng Q, Zheng W, Zhu X, Lu L, Shao H. Performance improvement in a Ti–Sb–Te phase change material by GaSb doping. CrystEngComm 2016. [DOI: 10.1039/c5ce02153g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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43
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Rao F, Song Z, Cheng Y, Liu X, Xia M, Li W, Ding K, Feng X, Zhu M, Feng S. Direct observation of titanium-centered octahedra in titanium-antimony-tellurium phase-change material. Nat Commun 2015; 6:10040. [PMID: 26610374 PMCID: PMC4674681 DOI: 10.1038/ncomms10040] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/27/2015] [Indexed: 12/02/2022] Open
Abstract
Phase-change memory based on Ti0.4Sb2Te3 material has one order of magnitude faster Set speed and as low as one-fifth of the Reset energy compared with the conventional Ge2Sb2Te5 based device. However, the phase-transition mechanism of the Ti0.4Sb2Te3 material remains inconclusive due to the lack of direct experimental evidence. Here we report a direct atom-by-atom chemical identification of titanium-centered octahedra in crystalline Ti0.4Sb2Te3 material with a state-of-the-art atomic mapping technology. Further, by using soft X-ray absorption spectroscopy and density function theory simulations, we identify in amorphous Ti0.4Sb2Te3 the titanium atoms preferably maintain the octahedral configuration. Our work may pave the way to more thorough understanding and tailoring of the nature of the Ti–Sb–Te material, for promoting the development of dynamic random access memory-like phase-change memory as an emerging storage-class memory to reform current memory hierarchy. Ti-Sb-Te is a promising phase change memory material however its phase transition mechanism is poorly understood. Here, the authors use microscopic and spectroscopic techniques to show that titanium-centered octahedra play a major role in boosting the performance of Ti-Sb-Te based phase change memory.
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Affiliation(s)
- Feng Rao
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, 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
| | - 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
| | - Xiaosong Liu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Mengjiao Xia
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Wei Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Keyuan Ding
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Xuefei Feng
- 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
| | - Songlin Feng
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
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44
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Chen Y, Ding Q, Zhang B, Han X, Zhang Z. B21-P-09The crystal micro-structure evolution of in-situ annealed phase change material TiSbTe film. Microscopy (Oxf) 2015. [DOI: 10.1093/jmicro/dfv253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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45
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Ahn C, Fong SW, Kim Y, Lee S, Sood A, Neumann CM, Asheghi M, Goodson KE, Pop E, Wong HSP. Energy-Efficient Phase-Change Memory with Graphene as a Thermal Barrier. NANO LETTERS 2015; 15:6809-6814. [PMID: 26308280 DOI: 10.1021/acs.nanolett.5b02661] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Phase-change memory (PCM) is an important class of data storage, yet lowering the programming current of individual devices is known to be a significant challenge. Here we improve the energy-efficiency of PCM by placing a graphene layer at the interface between the phase-change material, Ge2Sb2Te5 (GST), and the bottom electrode (W) heater. Graphene-PCM (G-PCM) devices have ∼40% lower RESET current compared to control devices without the graphene. This is attributed to the graphene as an added interfacial thermal resistance which helps confine the generated heat inside the active PCM volume. The G-PCM achieves programming up to 10(5) cycles, and the graphene could further enhance the PCM endurance by limiting atomic migration or material segregation at the bottom electrode interface.
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Affiliation(s)
| | | | - Yongsung Kim
- Samsung Advanced Institute of Technology (SAIT) , Suwon, 443-803, South Korea
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46
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Kolobov AV, Fons P, Tominaga J. Understanding Phase-Change Memory Alloys from a Chemical Perspective. Sci Rep 2015; 5:13698. [PMID: 26323962 PMCID: PMC4555180 DOI: 10.1038/srep13698] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 08/03/2015] [Indexed: 11/09/2022] Open
Abstract
Phase-change memories (PCM) are associated with reversible ultra-fast low-energy crystal-to-amorphous switching in GeTe-based alloys co-existing with the high stability of the two phases at ambient temperature, a unique property that has been recently explained by the high fragility of the glass-forming liquid phase, where the activation barrier for crystallisation drastically increases as the temperature decreases from the glass-transition to room temperature. At the same time the atomistic dynamics of the phase-change process and the associated changes in the nature of bonding have remained unknown. In this work we demonstrate that key to this behavior is the formation of transient three-center bonds in the excited state that is enabled due to the presence of lone-pair electrons. Our findings additionally reveal previously ignored fundamental similarities between the mechanisms of reversible photoinduced structural changes in chalcogenide glasses and phase-change alloys and offer new insights into the development of efficient PCM materials.
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Affiliation(s)
- A V Kolobov
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562, Japan
| | - P Fons
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562, Japan
| | - J Tominaga
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562, Japan
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47
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You BK, Byun M, Kim S, Lee KJ. Self-Structured Conductive Filament Nanoheater for Chalcogenide Phase Transition. ACS NANO 2015; 9:6587-6594. [PMID: 26039415 DOI: 10.1021/acsnano.5b02579] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ge2Sb2Te5-based phase-change memories (PCMs), which undergo fast and reversible switching between amorphous and crystalline structural transformation, are being utilized for nonvolatile data storage. However, a critical obstacle is the high programming current of the PCM cell, resulting from the limited pattern size of the optical lithography-based heater. Here, we suggest a facile and scalable strategy of utilizing self-structured conductive filament (CF) nanoheaters for Joule heating of chalcogenide materials. This CF nanoheater can replace the lithographical-patterned conventional resistor-type heater. The sub-10 nm contact area between the CF and the phase-change material achieves significant reduction of the reset current. In particular, the PCM cell with a single Ni filament nanoheater can be operated at an ultralow writing current of 20 μA. Finally, phase-transition behaviors through filament-type nanoheaters were directly observed by using transmission electron microscopy.
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Affiliation(s)
- Byoung Kuk You
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Myunghwan Byun
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Seungjun Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Keon Jae Lee
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
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48
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Zhu M, Xia M, Song Z, Cheng Y, Wu L, Rao F, Song S, Wang M, Lu Y, Feng S. Understanding the crystallization behavior of as-deposited Ti-Sb-Te alloys through real-time radial distribution functions. NANOSCALE 2015; 7:9935-9944. [PMID: 25970803 DOI: 10.1039/c4nr07408d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Phase change materials, successfully used in optical data-storage and non-volatile electronic memory, are well-known for their ultrafast crystallization speed. However, the fundamental understanding of their crystallization behavior, especially the nucleation process, is limited by present experimental techniques. Here, real-time radial distribution functions (RDFs), derived from the selected area electron diffractions, are employed as structural probes to comprehensively study both nucleation and subsequent growth stages of Ti-doped Sb2Te3 (TST) materials in the electron-irradiation crystallization process. It can be found that the incorporation of Ti atoms in Sb2Te3 forms wrong bonds such as Ti-Te, Ti-Sb, breaks the originally ordered atomic arrangement and diminishes the initial nucleus size of the as-deposited films, which results in better thermal stability. But these nuclei hardly grow until their sizes exceed a critical value, and then a rapid growth period starts. This means that an extended nucleation time is required to form the supercritical nuclei of TST alloys with higher concentration. Also, the increasing formation of four-membered rings, which served as nucleation sites, after doping excessive Ti is responsible for the change of the crystallization behavior from growth-dominated to nucleation-dominated.
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Affiliation(s)
- 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.
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49
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Xia M, Zhu M, Wang Y, Song Z, Rao F, Wu L, Cheng Y, Song S. Ti-Sb-Te alloy: a candidate for fast and long-life phase-change memory. ACS APPLIED MATERIALS & INTERFACES 2015; 7:7627-7634. [PMID: 25805549 DOI: 10.1021/acsami.5b00083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Phase-change memory (PCM) has great potential for numerous attractive applications on the premise of its high-device performances, which still need to be improved by employing a material with good overall phase-change properties. In respect to fast speed and high endurance, the Ti-Sb-Te alloy seems to be a promising candidate. Here, Ti-doped Sb2Te3 (TST) materials with different Ti concentrations have been systematically studied with the goal of finding the most suitable composition for PCM applications. The thermal stability of TST is improved dramatically with increasing Ti content. The small density change of T0.32Sb2Te3 (2.24%), further reduced to 1.37% for T0.56Sb2Te3, would greatly avoid the voids generated at phase-change layer/electrode interface in a PCM device. Meanwhile, the exponentially diminished grain size (from ∼200 nm to ∼12 nm), resulting from doping more and more Ti, enhances the adhesion between phase-change film and substrate. Tests of TST-based PCM cells have demonstrated a fast switching rate of ∼10 ns. Furthermore, because of the lower thermal conductivities of TST materials, compared with Sb2Te3-based PCM cells, T0.32Sb2Te3-based ones exhibit lower required pulse voltages for Reset operation, which largely decreases by ∼50% for T0.43Sb2Te3-based ones. Nevertheless, the operation voltages for T0.56Sb2Te3-based cells dramatically increase, which may be due to the phase separation after doping excessive Ti. Finally, considering the decreased resistance ratio, TixSb2Te3 alloy with x around 0.43 is proved to be a highly promising candidate for fast and long-life PCM applications.
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Affiliation(s)
- Mengjiao Xia
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- ‡University of the Chinese Academy of Sciences, Beijing 100080, People's Republic of China
| | - Min Zhu
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Yuchan Wang
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- ‡University of the Chinese Academy of Sciences, Beijing 100080, People's Republic of China
| | - Zhitang Song
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Feng Rao
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Liangcai Wu
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Yan Cheng
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Sannian Song
- †State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
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Xia M, Ding K, Rao F, Li X, Wu L, Song Z. Aluminum-centered tetrahedron-octahedron transition in advancing Al-Sb-Te phase change properties. Sci Rep 2015; 5:8548. [PMID: 25709082 PMCID: PMC4338431 DOI: 10.1038/srep08548] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/26/2015] [Indexed: 11/09/2022] Open
Abstract
Group IIIA elements, Al, Ga, or In, etc., doped Sb-Te materials have proven good phase change properties, especially the superior data retention ability over popular Ge2Sb2Te5, while their phase transition mechanisms are rarely investigated. In this paper, aiming at the phase transition of Al-Sb-Te materials, we reveal a dominant rule of local structure changes around the Al atoms based on ab initio simulations and nuclear magnetic resonance evidences. By comparing the local chemical environments around Al atoms in respective amorphous and crystalline Al-Sb-Te phases, we believe that Al-centered motifs undergo reversible tetrahedron-octahedron reconfigurations in phase transition process. Such Al-centered local structure rearrangements significantly enhance thermal stability of amorphous phase compared to that of undoped Sb-Te materials, and facilitate a low-energy amorphization due to the weak links among Al-centered and Sb-centered octahedrons. Our studies may provide a useful reference to further understand the underlying physics and optimize performances of all IIIA metal doped Sb-Te phase change materials, prompting the development of NOR/NAND Flash-like phase change memory technology.
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Affiliation(s)
- Mengjiao Xia
- 1] State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China [2] Graduate University of the Chinese Academy of Sciences, Beijing 100080, China
| | - Keyuan Ding
- 1] State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China [2] Graduate University of the Chinese Academy of Sciences, Beijing 100080, China
| | - Feng Rao
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Xianbin Li
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, 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
| | - 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
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