66 results on '"Xiang Shui Miao"'
Search Results
2. Heteroepitaxial passivation of Cs2AgBiBr6 wafers with suppressed ionic migration for X-ray imaging
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Bo Yang, Weicheng Pan, Haodi Wu, Guangda Niu, Jun-Hui Yuan, Kan-Hao Xue, Lixiao Yin, Xinyuan Du, Xiang-Shui Miao, Xiaoquan Yang, Qingguo Xie, and Jiang Tang
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Science - Abstract
Ionic migration degrades not only the characteristics of halide perovskite solar cells, but also those of perovskite X-ray detectors. Here Yang et al. employ heteroepitaxial BiOBr to passivate Cs2AgBiBr6 double perovskite, which suppresses ionic migration and obtain high performance X-ray detectors.
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- 2019
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3. Resistive Switching Characteristics of HfO x -Based Memristor by Inserting GeTe Layer
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Hua-Nan Liang, Na Bai, Lan-Qing Zou, Hua-Jun Sun, Kan-Hao Xue, Wei-Ming Cheng, Hong Lu, and Xiang-Shui Miao
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Electrical and Electronic Engineering ,Electronic, Optical and Magnetic Materials - Published
- 2023
4. Recent Progress on Memristive Convolutional Neural Networks for Edge Intelligence
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Yi-Fan Qin, Han Bao, Feng Wang, Jia Chen, Yi Li, and Xiang-Shui Miao
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convolutional neural network accelerators ,edge intelligence ,long short-term memory neural networks ,memristors ,quantization ,Computer engineering. Computer hardware ,TK7885-7895 ,Control engineering systems. Automatic machinery (General) ,TJ212-225 - Abstract
Recently, due to the development of big data and computer technology, artificial intelligence (AI) has received extensive attention and made great progress. Edge intelligence pushes the computing center of AI from the cloud to individual users, making AI closer to life, but at the same time puts forward higher requirements for the realization of hardware, especially for edge acceleration. Taking convolutional neural networks (CNNs) as an example, which show excellent problem‐solving capabilities in different fields of academia and industry, it still faces issues of enormous computing volume and complex mapping architecture. Based on the computing‐in‐memory property and parallel multiply accumulate (MAC) operations of the emerging nonvolatile memristor arrays, herein the recent research progress of the edge intelligence memristive convolution accelerator is summarized. Furthermore, aiming at improving memristive convolutional accelerators, two potential optimization schemes are also discussed: The compression methods represented by quantization show great potential for static image processing, and the combination of a CNN with a long short‐term memory (LSTM) neural network makes up for the CNN's shortcomings of dynamic target processing. Finally, the future challenges and opportunities of edge intelligence accelerators based on memristor arrays are also discussed.
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- 2020
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5. Memristive Fast-Canny Operation for Edge Detection
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Jing Tian, Hou-Ji Zhou, Han Bao, Jia Chen, Xiao-Di Huang, Jian-Cong Li, Ling Yang, Yi Li, and Xiang-Shui Miao
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Electrical and Electronic Engineering ,Electronic, Optical and Magnetic Materials - Published
- 2022
6. Oxygen migration around the filament region in HfOx memristors
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Ge-Qi Mao, Kan-Hao Xue, Ya-Qian Song, Wei Wu, Jun-Hui Yuan, Li-Heng Li, Huajun Sun, Shibing Long, and Xiang-Shui Miao
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Physics ,QC1-999 - Abstract
The exact composition and structure of conductive filaments in hafnia-based memristors are still not fully understood, but recent theoretical investigations reveal that hexagonal HfOx phases close to the h.c.p. Hf structure are probable filament candidates. In this work we list h.c.p. Hf, Hf6O, Hf3O and Hf2O as possible phases for the filament in hafnia memristors. Their differences in lattice parameters, electronic structures and O charge states are studied in details. Migration of O ions for both in-plane and out-of-plane directions in these phases is investigated using first-principles calculations. Both single-phase supercells and filament-in-dielectric models are used for migration barrier calculations, while the latter is proven to be more accurate for the c-direction. The migration of O ions is fastest in metal Hf, while slowest in Hf2O. The existence of O interstitials in Hf tends to hinder the transport of O.
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- 2019
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7. The Role of Arsenic in the Operation of Electrical Threshold Switches
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Renjie Wu, Rongchuan Gu, Tamihiro Gotoh, Zihao Zhao, Yuting Sun, Shujing Jia, Xiang Shui Miao, Min Zhu, Ming Xu, Stephen Elliott, and Zhitang Song
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Arsenic is one of the most frequently used elements for doping conventional silicon-based semiconductors and particularly in emerging phase-change-memory (PCM) chips, yet the detailed functional mechanism as well as its experimental demonstration is still lacking in the latter in spite of its wide application. Here, we fabricate chalcogenide-based ovonic threshold switching (OTS) selectors, which are essential units for suppressing sneak currents in 3D PCM arrays, with various As concentrations. We discovered that incorporation of 20 at. % As brings a more than 100 ℃ increase in crystallization temperature, remarkably improving the switching repeatability and prolonging the device lifetime. These benefits arise from strengthened As-S bonds and sluggish atomic migration after As incorporation, as demonstrated by molecular-dynamics simulations. As a result, the addition of As reduces the leakage current by more than an order of magnitude and significantly suppresses the operational voltage drift, ultimately enabling a backend-of-the-line (BEOL)-compatible OTS selector with > 12 MA/cm2 on-current, >104 on/off ratio, ~ 10 ns speed, and a lifetime approaching 1010 cycles after 450 ℃ annealing. These performance enhancements can be explained by an As-induced increase of the band gap and of trap states, as determined by experimental photothermal deflection spectroscopy. Mechanistically, this is due to abundant defect states associated with Ge-Ge chains introduced by As-Ge and As-S bonds. These findings allow the use of precise control of the As concentration in OTS materials for improved-performance high-density 3D PCM applications.
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- 2023
8. Pt/Al2O3/TaO X /Ta Self-Rectifying Memristor With Record-Low Operation Current (<2 pA), Low Power (fJ), and High Scalability
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Sheng-Guang Ren, Run Ni, Xiao-Di Huang, Yi Li, Kan-Hao Xue, and Xiang-Shui Miao
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Electrical and Electronic Engineering ,Electronic, Optical and Magnetic Materials - Published
- 2022
9. Ultrafast and stable phase transition realized in MoTe2-based memristive devices
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Hui-Kai He, Yong-Bo Jiang, Jun Yu, Zi-Yan Yang, Chao-Fan Li, Ting-Ze Wang, De-Quan Dong, Fu-Wei Zhuge, Ming Xu, Zhi-Yi Hu, Rui Yang, and Xiang-Shui Miao
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Mechanics of Materials ,Process Chemistry and Technology ,General Materials Science ,Electrical and Electronic Engineering - Abstract
An electric-field induced phase transition between semiconducting 2H and metallic 1T′ phases in a MoTe2 device is demonstrated for the first time. The phase transition exhibits faster switching compared with phase-change random-access memory (PCRAM), and shows more controllable switching than conventional memristive devices.
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- 2022
10. Melting-Free Phase-Change Memory for Associative Learning
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Da-You Zhang, Si-Qi Wang, Zi-Jian Tang, Xiang-Shui Miao, and Yu-Hui He
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- 2022
11. Color printing enabled by phase change materials on paper substrate
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Hong-Kai Ji, Hao Tong, Hang Qian, Nian Liu, Ming Xu, and Xiang-Shui Miao
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Physics ,QC1-999 - Abstract
We have coated phase change materials (PCMs) on rough and flexible substrates to achieve multicolor changeable devices. The principle of the device is based on an earlier discovery that lights have strong interference effect in PCM films, leading to various colors by reflection. In this work, paper substrates are laminated by parylene layers to protect the device from water before coated with functional PCM films. The PCM-based color printing (PCP) on paper is not affected by rough surfaces and shows a similar color appearance as that on smooth surfaces. In particular, the color-printed device can be patterned by UV lithography to display a clear and tunable optical image, and it exhibits a low sensitivity to the angle of view. Such PCP has potential applications for low-cost, disposable, and flexible displays.
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- 2017
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12. In-memory sparse matrix multiplication with a low-power self-rectifying memristor array
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Jiangcong Li, Shengguang Ren, Yi Li, Ling Yang, Yingjie Yu, Run Ni, Houji Zhou, Han Bao, Yuhui He, Jia Chen, Han Jia, and Xiang Shui Miao
- Abstract
Memristor-enabled in-memory computing provides an unconventional computing paradigm to surpass the energy efficiency of von Neumann computers. However, owing to the physical limitation of the crossbar structure, although the memristor array is desirable for dense computation, it suffers from significant performance degradation in both energy and area efficiency when processing sparse linear algebra operations. In this work, we report a highly efficient in-memory sparse computing system based on the self-rectifying memristor, which originates from the joint effort of devices and algorithms and is used to solve computational modelling problems. This system is expected to have 74.9 – 19.6 TOPS / W energy efficiency for 2-bit to 8-bit sparse computation in computational modelling tasks. Compared to the previous in-memory computing hardware, our system provides over one order of magnitude improvement in energy efficiency with more than two orders of magnitude reduction in hardware overhead. This work could pave the road towards a highly efficient, unconventional computing solution for high-performance computing.
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- 2022
13. Ultrafast synergistic excitation for in-situ computing
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Lei Ye, Lei Tong, Yali Bi, Yilun Wang, Xinyu Huang, Zhuiri Peng, Zheng Li, Langlang Xu, Runfeng Lin, Sihan Chen, WenHao Shi, Ming Tang, Hui Yu, Xinliang Zhang, Ping Wang, and Xiang Shui Miao
- Abstract
Nonlinear optical phenomena (NLOPs) in two-dimensional (2D) materials can be envisioned for neuromorphic functions at the device and related system level. But it has been attended rarely that transition among multi-energy states as one origin of NLOPs directly used for neuromorphic functions, which is assisted to understand nature of device-level nonlinear optical neuromorphic performance. Here we introduced a pump-probe-control technology to reveal multi-energy-state transition in multilayer molybdenum disulfide, enhancing nonlinear signals by transitions from two-photon absorption to synergistic excited states absorption and enabling an in-situ computing concept within an array of pure 2D flakes. Optical weighted average calculation and artificial neural network were realized without the fabrication of complex extrinsic structures, while preserving the femtosecond speed and femto-Joule power consumption, revealing the feasibility of pump-probe-control technology for nonlinear neuromorphic functions.
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- 2022
14. In-memory Search with Memristors for Highly Efficient Similarity-Measurement-Based Data Mining
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Yi Li, Ling Yang, Xiao-Di Huang, Houji Zhou, Yingjie Yu, Han Bao, Jiangcong Li, Shengguang Ren, Feng Wang, Lei Ye, Yuhui He, Jia Chen, Guiyou Pu, Xiang Li, and Xiang Shui Miao
- Abstract
Similarity search, that is, finding similar items in massive data, is a fundamental computing problem in many fields such as data mining, and information retrieval. However, for large-scale and high-dimension data, it suffers from high computational complexity, requiring tremendous computation resources. Here, based on the one-selector-one-resistor memristors, for the first time, we propose an in-memory search (IMS) system with two innovative designs. First, by exploiting the natural distribution law of the devices resistance, a hardware local sensitive hash encoder has been designed to transform the real-valued vectors into more efficient binary codes. Second, a compact memristive ternary content addressable memory is developed to calculate the Hamming distances between the binary codes in parallel. Our IMS system demonstrated a 168× energy efficiency improvement over all-transistors counterparts in clustering and classification tasks, while achieving a software-comparable accuracy, thus providing a low-complexity and low-power solution for in-memory data mining applications.
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- 2022
15. 2022 roadmap on neuromorphic devices and applications research in China
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Qing Wan, Changjin Wan, Huaqiang Wu, Yuchao Yang, Xiaohe Huang, Peng Zhou, Lin Chen, Tian-Yu Wang, Yi Li, Kan-Hao Xue, Yu-Hui He, Xiang-Shui Miao, Xi Li, Chenchen Xie, Houpeng Chen, Zhitang Song, Hong Wang, Yue Hao, Junyao Zhang, Jia Huang, Zheng Yu Ren, Li Qiang Zhu, Jianyu Du, Chen Ge, Yang Liu, Guanglong Ding, Ye Zhou, Su-Ting Han, Guosheng Wang, Xiao Yu, Bing Chen, Zhufei Chu, Lunyao Wang, Yinshui Xia, Chen Mu, Feng Lin, Chixiao Chen, Bojun Cheng, Yannan Xing, Weitao Zeng, Hong Chen, Lei Yu, Giacomo Indiveri, and Ning Qiao
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General Medicine - Abstract
The data throughput in the von Neumann architecture-based computing system is limited by its separated processing and memory structure, and the mismatching speed between the two units. As a result, it is quite difficult to improve the energy efficiency in conventional computing system, especially for dealing with unstructured data. Meanwhile, artificial intelligence and robotics nowadays still behave poorly in autonomy, creativity, and sociality, which has been considered as the unimaginable computational requirement for sensorimotor skills. These two plights have urged the imitation and replication of the biological systems in terms of computing, sensing, and even motoring. Hence, the so-called neuromorphic system has drawn worldwide attention in recent decade, which is aimed at addressing the aforementioned needs from the mimicking of neural system. The recent developments on emerging memory devices, nanotechnologies, and materials science have provided an unprecedented opportunity for this aim.
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- 2022
16. Large On/Off and Rectification Ratios, Self-Compliance, High-Uniformity in Pt/Al2O3/TaOx/Ta Self-Rectifying Memristors
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Sheng-Guang Ren, Run Ni, Xiao-Di Huang, Yi Li, and Xiang-Shui Miao
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- 2021
17. Two-dimensional silicon chalcogenides with high carrier mobility for photocatalytic water splitting
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Jun-Hui Yuan, Xiaomin Cheng, Ming Xu, Xiang-Shui Miao, Sheng Wang, Yun-Lai Zhu, Kan-Hao Xue, and Ya-Qian Song
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Condensed Matter - Materials Science ,Electron mobility ,Materials science ,Silicon ,business.industry ,Band gap ,020502 materials ,Mechanical Engineering ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,chemistry.chemical_element ,02 engineering and technology ,Semiconductor ,0205 materials engineering ,chemistry ,Mechanics of Materials ,Water splitting ,Optoelectronics ,General Materials Science ,Density functional theory ,business ,Absorption (electromagnetic radiation) ,Photocatalytic water splitting - Abstract
Highly-efficient water splitting based on solar energy is one of the most attractive research focuses in the energy field. Searching for more candidate photocatalysts that can work under visible-light irradiation are highly demanded. Herein, using first principle calculations based on density functional theory, we predict that the two dimensional silicon chalcogenides, i.e. SiX (X=S, Se, Te) monolayers, as semiconductors with 2.43 eV~3.00 eV band gaps, exhibit favorable band edge positions for photocatalytic water splitting. The optical adsorption spectra demonstrate that the SiX monolayers have pronounced optical absorption in the visible light region. Moreover, the band gaps and band edge positions of silicon chalcogenides monolayers can be tuned by applying biaxial strain or increasing the number of layers, in order to better fit the redox potentials of water. The combined novel electronic, high carrier mobility, and optical properties render the two dimensional SiX a promising photocatalyst for water splitting., 5 figures, 2 tables
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- 2019
18. Reconfigurable Boolean Logic in Memristive Crossbar: The Principle and Implementation
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Ting-Chang Chang, Long Cheng, Xiang-Shui Miao, Yi Li, Simon M. Sze, Zhuo-Rui Wang, and Si-Yu Hu
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Flexibility (engineering) ,Adder ,Computer science ,NAND gate ,Memristor ,Electronic, Optical and Magnetic Materials ,law.invention ,symbols.namesake ,In-Memory Processing ,law ,symbols ,Electrical and Electronic Engineering ,Crossbar switch ,Arithmetic ,XOR gate ,Von Neumann architecture - Abstract
In-memory computing based on memristive logic is considered as a prospective non von Neumann computing paradigm. In this letter, we systematically analyze the four-variable logic method and map it into the operation of two anti-serial complementary memristors in the crossbar array architecture. Arbitrary Boolean logic can be implemented within three cycles with the experimental evidence of reconfigurable NAND, NOR, and XOR logic using Pt/HfO2/TiN devices. Taking advantage of the functional flexibility, a parallel 1-bit full adder that can be realized in 8 cycles within a $\textsf {4}\times \textsf {3}$ array has been designed and verified in simulation.
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- 2019
19. KTlO: a metal shrouded 2D semiconductor with high carrier mobility and tunable magnetism
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Xiang-Shui Miao, Jiafu Wang, Jun-Hui Yuan, Kan-Hao Xue, Ya-Qian Song, Li-Heng Li, and Ming Xu
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Electron mobility ,Materials science ,Magnetism ,business.industry ,Band gap ,Doping ,02 engineering and technology ,Electronic structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Semiconductor ,Monolayer ,Optoelectronics ,General Materials Science ,Direct and indirect band gaps ,0210 nano-technology ,business - Abstract
Two-dimensional materials with high carrier mobility and tunable magnetism are in high demand for nanoelectronic and spintronic applications. Herein, we predict a novel two-dimensional monolayer KTlO that possesses an indirect band gap of 2.25 eV (based on HSE06 calculations) and high carrier mobility (450 cm2 V-1 s-1 for electrons and 160 cm2 V-1 s-1 for holes) by means of ab initio calculations. The electron mobility can be increased up to 26 280 cm2 V-1 s-1 and 54 150 cm2 V-1 s-1 for bilayer and trilayer KTlO, respectively. The KTlO monolayer has a calculated cleavage energy of 0.56 J m-2, which suggests exfoliation of the bulk material as a viable means for the preparation of mono- and few-layer materials. Remarkably, the KTlO monolayer demonstrates tunable magnetism and half-metallicity with hole doping, which are attributed to the novel Mexican-hat-like bands and van Hove singularities in its electronic structure. Furthermore, monolayer KTlO exhibits moderate optical absorption over the visible light and ultraviolet regions. The band gap value and band characteristics of monolayer KTlO can be substantially manipulated by biaxial and uniaxial strains to meet the requirement of various applications. All these novel properties make monolayer KTlO a promising functional material for future nanoelectronic and spintronic applications.
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- 2019
20. A High‐Performance Ag/TiN/HfO x /HfO y /HfO x /Pt Diffusive Memristor for Calibration‐Free True Random Number Generator
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Yi‐Fan Lu, Hao‐Yang Li, Yi Li, Li‐Heng Li, Tian‐Qing Wan, Ling Yang, Wen‐Bing Zuo, Kan‐Hao Xue, and Xiang‐Shui Miao
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Electronic, Optical and Magnetic Materials - Published
- 2022
21. Enhancing LiAlO
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Yaoyao, Fu, Boyi, Dong, Wan-Ching, Su, Chih-Yang, Lin, Kuan-Ju, Zhou, Ting-Chang, Chang, Fuwei, Zhuge, Yi, Li, Yuhui, He, Bin, Gao, and Xiang-Shui, Miao
- Abstract
Although good performance has been reported in shallow neural networks, the application of memristor synapses towards realistic deep neural networks has met more stringent requirements on the synapse properties, particularly the high precision and linearity of the synaptic analog weight tuning. In this study, a LiAlOX memristor synapse was fabricated and optimized to address these demands. By delicately tuning the initial conductance states, 120-level continuously adjustable conductance states were obtained and the nonlinearity factor was substantially reduced from 8.96 to 0.83. The significant enhancements were attributed to the reduced Schottky barrier height (SBH) between the filament tip and the electrode, which was estimated from the measured I-V curves. Furthermore, a deep neural network for realistic action recognition task was constructed, and the recognition accuracy was found to be increased from 15.1% to 91.4% on the Weizmann video dataset by adopting the above-described device optimization method.
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- 2020
22. Pt
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Jun-Hui, Yuan, Li-Heng, Li, Wei, Zhang, Kan-Hao, Xue, Chundong, Wang, Jiafu, Wang, Xiang-Shui, Miao, and Xiao Cheng, Zeng
- Abstract
Electrocatalysts with high activities toward multiple electrode reactions are scarce and therefore highly sought. Here, we investigate the electrocatalytic performance of the two-dimensional (2D) Pt
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- 2020
23. Filament-to-dielectric band alignments in $$\hbox {TiO}_{2}$$ TiO 2 and $$\hbox {HfO}_{2}$$ HfO 2 resistive RAMs
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Kan-Hao Xue, Xiang-Shui Miao, and Ze-Han Wu
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010302 applied physics ,Resistive touchscreen ,Materials science ,Band gap ,Schottky barrier ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Protein filament ,Crystallography ,Ab initio quantum chemistry methods ,Modeling and Simulation ,Resistive switching ,0103 physical sciences ,Electrical and Electronic Engineering ,0210 nano-technology ,Ohmic contact - Abstract
The next-generation nonvolatile memory storage may well be based on resistive random access memories (RRAMs). $$\hbox {TiO}_{2}$$ and $$\hbox {HfO}_{2}$$ have been widely used as the resistive switching layer for RRAM devices. However, the electronic properties of the filament-to-dielectric interfaces are still not well understood yet, compared to those of the electrodes and the dielectric. In this work, we study the electronic structures of three typical filament and dielectric structures, $$\hbox {Ti}_{4}\hbox {O}_{7}/\hbox {TiO}_{2}$$ , $$\hbox {Hf}_{2}\hbox {O}_{3}/\hbox {HfO}_{2}$$ and $$\hbox {Hf}/\hbox {HfO}_{2}$$ , using ab initio calculations. We implement the GGA-1/2 method, which rectifies the band gaps of GGA through self-energy correction. Our calculation predicts an ohmic contact for the $$\hbox {Ti}_{4}\hbox {O}_{7}/\hbox {TiO}_{2}$$ interface, where the defective $$\hbox {Ti}_{4}\hbox {O}_{7}$$ phase was experimentally identified as the filament composition in $$\hbox {TiO}_{2}$$ . However, there is a finite Schottky barrier existing in either $$\hbox {Hf}_{2}\hbox {O}_{3}/\hbox {HfO}_{2}$$ interface (1.96 eV) or $$\hbox {Hf}/\hbox {HfO}_{2}$$ interface (0.61 eV), the two probable filament–dielectric configurations in hafnia-based RRAM. Our results suggest that the distinct filament-to-dielectric band alignments in $$\hbox {TiO}_{x}$$ and $$\hbox {HfO}_{x}$$ systems account for the much larger resistance window for the latter.
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- 2017
24. Functionally Complete Boolean Logic in 1T1R Resistive Random Access Memory
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Yu-Ting Su, Tian-Jian Chu, Ting-Chang Chang, Xiang-Shui Miao, Tsung-Ming Tsai, Kuan-Chang Chang, Yi Li, Simon M. Sze, Zhuo-Rui Wang, and Ya-Xiong Zhou
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010302 applied physics ,Structure (mathematical logic) ,Computer science ,Boolean circuit ,Functional completeness ,Initialization ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Resistive random-access memory ,Stateful firewall ,Logic gate ,0103 physical sciences ,State (computer science) ,Electrical and Electronic Engineering ,Arithmetic ,0210 nano-technology ,Hardware_LOGICDESIGN - Abstract
Nonvolatile stateful logic through RRAM is a promising route to build in-memory computing architecture. In this letter, a logic methodology based on 1T1R structure has been proposed to implement functionally complete Boolean logics. Arbitrary logic functions could be realized in two steps: initialization and writing. An additional read step is required to read out the logic result, which is in situ stored in the nonvolatile resistive state of the memory. Cascade problem in building larger logic circuits is also discussed. Our 1T1R logic device and operation method could be beneficial for massive integration and practical application of RRAM-based logic.
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- 2017
25. Nonvolatile reconfigurable sequential logic in a HfO2 resistive random access memory array
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Ling-Yi Shih, Kuan-Chang Chang, Zhuo-Rui Wang, Simon M. Sze, Shibing Long, Ya-Xiong Zhou, Xiang-Shui Miao, Yu-Ting Su, Ting-Chang Chang, and Yi Li
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010302 applied physics ,Sequential logic ,business.industry ,Computer science ,Logic family ,02 engineering and technology ,Parallel computing ,021001 nanoscience & nanotechnology ,01 natural sciences ,Programmable logic array ,Programmable logic device ,Programmable Array Logic ,Logic synthesis ,Logic gate ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,business ,Computer hardware ,Hardware_LOGICDESIGN ,Logic optimization - Abstract
Resistive random access memory (RRAM) based reconfigurable logic provides a temporal programmable dimension to realize Boolean logic functions and is regarded as a promising route to build non-von Neumann computing architecture. In this work, a reconfigurable operation method is proposed to perform nonvolatile sequential logic in a HfO2-based RRAM array. Eight kinds of Boolean logic functions can be implemented within the same hardware fabrics. During the logic computing processes, the RRAM devices in an array are flexibly configured in a bipolar or complementary structure. The validity was demonstrated by experimentally implemented NAND and XOR logic functions and a theoretically designed 1-bit full adder. With the trade-off between temporal and spatial computing complexity, our method makes better use of limited computing resources, thus provides an attractive scheme for the construction of logic-in-memory systems.
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- 2017
26. Lead-Free Halide Rb
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Bo, Yang, Lixiao, Yin, Guangda, Niu, Jun-Hui, Yuan, Kan-Hao, Xue, Zhifang, Tan, Xiang-Shui, Miao, Ming, Niu, Xinyuan, Du, Haisheng, Song, Efrat, Lifshitz, and Jiang, Tang
- Abstract
Scintillators are widely utilized for radiation detections in many fields, such as nondestructive inspection, medical imaging, and space exploration. Lead halide perovskite scintillators have recently received extensive research attention owing to their tunable emission wavelength, low detection limit, and ease of fabrication. However, the low light yields toward X-ray irradiation and the lead toxicity of these perovskites severely restricts their practical application. A novel lead-free halide is presented, namely Rb
- Published
- 2019
27. Hot-Pressed CsPbBr
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Weicheng, Pan, Bo, Yang, Guangda, Niu, Kan-Hao, Xue, Xinyuan, Du, Lixiao, Yin, Muyi, Zhang, Haodi, Wu, Xiang-Shui, Miao, and Jiang, Tang
- Abstract
An X-ray detector with high sensitivity would be able to increase the generated signal and reduce the dose rate; thus, this type of detector is beneficial for applications such as medical imaging and product inspection. The inorganic lead halide perovskite CsPbBr
- Published
- 2019
28. Heteroepitaxial passivation of Cs
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Bo, Yang, Weicheng, Pan, Haodi, Wu, Guangda, Niu, Jun-Hui, Yuan, Kan-Hao, Xue, Lixiao, Yin, Xinyuan, Du, Xiang-Shui, Miao, Xiaoquan, Yang, Qingguo, Xie, and Jiang, Tang
- Subjects
Materials for devices ,Optics and photonics ,Electronic devices ,Article ,Materials science - Abstract
X-ray detectors are broadly utilized in medical imaging and product inspection. Halide perovskites recently demonstrate excellent performance for direct X-ray detection. However, ionic migration causes large noise and baseline drift, limiting the detection and imaging performance. Here we largely eliminate the ionic migration in cesium silver bismuth bromide (Cs2AgBiBr6) polycrystalline wafers by introducing bismuth oxybromide (BiOBr) as heteroepitaxial passivation layers. Good lattice match between BiOBr and Cs2AgBiBr6 enables complete defect passivation and suppressed ionic migration. The detector hence achieves outstanding balanced performance with a signal drifting one order of magnitude lower than all previous studies, low noise (1/f noise free), a high sensitivity of 250 µC Gy air−1 cm–2, and a spatial resolution of 4.9 lp mm−1. The wafer area could be easily scaled up by the isostatic-pressing method, together with the heteroepitaxial passivation, strengthens the competitiveness of Cs2AgBiBr6-based X-ray detectors as next-generation X-ray imaging flat panels., Ionic migration degrades not only the characteristics of halide perovskite solar cells, but also those of perovskite X-ray detectors. Here Yang et al. employ heteroepitaxial BiOBr to passivate Cs2AgBiBr6 double perovskite, which suppresses ionic migration and obtain high performance X-ray detectors.
- Published
- 2018
29. Neuronal dynamics in HfO
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Sungjun, Kim, Jia, Chen, Ying-Chen, Chen, Min-Hwi, Kim, Hyungjin, Kim, Min-Woo, Kwon, Sungmin, Hwang, Muhammad, Ismail, Yi, Li, Xiang-Shui, Miao, Yao-Feng, Chang, and Byung-Gook, Park
- Subjects
Neurons ,Silicon ,Neuronal Plasticity ,Long-Term Potentiation ,Models, Neurological ,Temperature ,Brain ,Oxides ,Oxygen ,Semiconductors ,Synapses ,Aluminum Oxide ,Humans ,Electronics ,Nerve Net ,Electrodes ,Hafnium - Abstract
We studied the pseudo-homeothermic synaptic behaviors by integrating complimentary metal-oxide-semiconductor-compatible materials (hafnium oxide, aluminum oxide, and silicon substrate). A wide range of temperatures, from 25 °C up to 145 °C, in neuronal dynamics was achieved owing to the homeothermic properties and the possibility of spike-induced synaptic behaviors was demonstrated, both presenting critical milestones for the use of emerging memristor-type neuromorphic computing systems in the near future. Biological synaptic behaviors, such as long-term potentiation, long-term depression, and spike-timing-dependent plasticity, are developed systematically, and comprehensive neural network analysis is used for temperature changes and to conform spike-induced neuronal dynamics, providing a new research regime of neurocomputing for potentially harsh environments to overcome the self-heating issue in neuromorphic chips.
- Published
- 2018
30. Salt-Gradient Approach for Regulating Capture-to-Translocation Dynamics of DNA with Nanochannel Sensors
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Masateru Taniguchi, Ralph H. Scheicher, Yuhui He, Makusu Tsutsui, and Xiang Shui Miao
- Subjects
Fluid Flow and Transfer Processes ,Chemistry ,Process Chemistry and Technology ,Dynamics (mechanics) ,Electrical potentials ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Nanopore ,Present method ,Fluidics ,Nanopore sequencing ,0210 nano-technology ,Instrumentation ,DNA ,Hydrodynamic flow - Abstract
Understanding the physical mechanisms that govern the ion and fluidic transport in salt-concentration-based nanochannel/nanopore systems is essential for the potential applications in bioanalysis. One central challenge is to interpret the observed four-stage change from osmosis to the reverse one with increasing salt gradient. Here we provide a unified model that outlines the intriguing role of two competing factors, the exclusion- and diffusion-induced electrical potentials. We demonstrate theoretically a direction control of a hydrodynamic flow via the salt gradient. Based on this, we also propose a salt-gradient approach for regulating DNA motion in nanochannels that enables voltage-free single-molecule capture with a significantly low translocation speed. The present method would be used as a useful protocol to overcome the key hurdle of tailoring the capture-to-translocation dynamics of polynucleotides for nanopore sequencing.
- Published
- 2016
31. Implementation of Functionally Complete Boolean Logic and 8-Bit Adder in CMOS Compatible 1T1R RRAMs for In-Memory Computing
- Author
-
Simon M. Sze, Zhuo-Rui Wang, Kan-Hao Xue, Yu-Ting Su, Ting-Chang Chang, Kang-Sheng Yin, Yi Li, Ya-Xiong Zhou, Long Cheng, and Xiang-Shui Miao
- Subjects
010302 applied physics ,Adder ,Computational complexity theory ,Computer science ,8-bit ,02 engineering and technology ,Parallel computing ,Construct (python library) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Resistive random-access memory ,symbols.namesake ,In-Memory Processing ,Logic gate ,0103 physical sciences ,symbols ,0210 nano-technology ,Von Neumann architecture - Abstract
RRAM is a promising candidate to construct in-memory computing architecture which can break through the von Neumann bottleneck. Taking advantage of the CMOS compatible 1T1R RRAM, functionally complete Boolean logics can be realized within two steps in a single unit that can suppress sneak pass problem and avoid cascading problem partially. In addition, an 8-bit pre- calculation adder with low computation complexity is designed and demonstrated experimentally to verify the feasibility and efficiency of 1T1R based in-memory computing architecture, which is applicable to future energy-efficient information processing systems.
- Published
- 2018
32. Observation of carrier localization in cubic crystalline Ge
- Author
-
Hang, Qian, Hao, Tong, Ming-Ze, He, Hong-Kai, Ji, Ling-Jun, Zhou, Ming, Xu, and Xiang-Shui, Miao
- Subjects
sense organs ,Article - Abstract
The tunable disorder of vacancies upon annealing is an important character of crystalline phase-change material Ge2Sb2Te5 (GST). A variety of resistance states caused by different degrees of disorder can lead to the development of multilevel memory devices, which could bring a revolution to the memory industry by significantly increasing the storage density and inspiring the neuromorphic computing. This work focuses on the study of disorder-induced carrier localization which could result in multiple resistance levels of crystalline GST. To analyze the effect of carrier localization on multiple resistant levels, the intrinsic field effect (the change in surface conductance with an applied transverse electric field) of crystalline GST was measured, in which GST films were annealed at different temperatures. The field effect measurement is an important complement to conventional transport measurement techniques. The field effect mobility was acquired and showed temperature activation, a hallmark of carrier localization. Based on the relationship between field effect mobility and annealing temperature, we demonstrate that the annealing shifts the mobility edge towards the valence-band edge, delocalizing more carriers. The insight of carrier transport in multilevel crystalline states is of fundamental relevance for the development of multilevel phase change data storage.
- Published
- 2017
33. Nonvolatile reconfigurable sequential logic in a HfO
- Author
-
Ya-Xiong, Zhou, Yi, Li, Yu-Ting, Su, Zhuo-Rui, Wang, Ling-Yi, Shih, Ting-Chang, Chang, Kuan-Chang, Chang, Shi-Bing, Long, Simon M, Sze, and Xiang-Shui, Miao
- Abstract
Resistive random access memory (RRAM) based reconfigurable logic provides a temporal programmable dimension to realize Boolean logic functions and is regarded as a promising route to build non-von Neumann computing architecture. In this work, a reconfigurable operation method is proposed to perform nonvolatile sequential logic in a HfO
- Published
- 2017
34. Mimicking the brain functions of learning, forgetting and explicit/implicit memories with SrTiO
- Author
-
Xue-Bing, Yin, Rui, Yang, Kan-Hao, Xue, Zheng-Hua, Tan, Xiao-Dong, Zhang, Xiang-Shui, Miao, and Xin, Guo
- Abstract
To implement the complex brain functions of learning, forgetting and memory in a single electronic device is very advantageous for realizing artificial intelligence. As a proof of concept, memristive devices with a simple structure of Ni/Nb-SrTiO
- Published
- 2016
35. Impact of Water-Depletion Layer on Transport in Hydrophobic Nanochannels
- Author
-
Masateru Taniguchi, Yuhui He, Makusu Tsutsui, and Xiang Shui Miao
- Subjects
Electrokinetic phenomena ,Depletion region ,Chemical physics ,Chemistry ,Ionic bonding ,Redistribution (chemistry) ,Nanotechnology ,Water depletion ,Fluidics ,Surface charge ,Analytical Chemistry ,Hydrophobe - Abstract
Recent experiments showed that by fabricating nanofluidic channels with hydrophobic materials, the measured amplitudes of both electroosmotic flow (EOF) and ionic current deviated significantly from the conventional electrokinetic modeling indication. Among these unexpected observations, the complicated dependence of EOF on the surface charge concentration of the channel wall remains most confusing. In this work we give a complete and unified picture for the phenomena by outlining the competing two mechanisms in the water-depletion layer around the channel wall: the decreasing trend of fluidic flow due to the redistribution of net charges, and the increasing trend because of the reduced solution viscosity there. Our quantitative evaluation illustrates that the alternate dominating by the two mechanisms leads to the observed transport behaviors. Furthermore, by considering the decreasing of ionic mobility in the depletion layer, our calculations show quantitative agreement with the latest experiments using BN nanotube channels.
- Published
- 2015
36. Ultrafast crystallization and thermal stability of In-Ge doped eutectic [Sb.sub.70]Te.sub.30] phase change material
- Author
-
Mei Ling Lee, Xiang Shui Miao, Lee Hou Ting, and Lu Ping Shi
- Subjects
Crystallization -- Analysis ,Indium -- Optical properties ,Semiconductor doping -- Analysis ,Germanium -- Optical properties ,Physics - Abstract
A study was conducted to examine the effect of In and Ge doping in the form of [In.sub.2][Ge.sub.8][Sb.sub.85][Te.sub.5] on optical and thermal properties of eutectic [Sb.sub.70][Te.sub.30] alloys. The use of ultrafast and thermally stable [In.sub.2][Ge.sub.8][Sb.sub.85][Te.sub.5] phase change material as mask layer in aperture-type super-resolution near-field phase change disk was realized to increase the carrier-to-noise ratio and thermal stability.
- Published
- 2008
37. Error Correction Code Failure Rate Analysis for Parity-Check-Coded Optical Recording Systems
- Author
-
Zhiliang Qin, Kui Cai, L. P. Shi, Xiang Shui Miao, and Kees A. Schouhamer Immink
- Subjects
Physics and Astronomy (miscellaneous) ,Computer science ,Concatenated error correction code ,General Engineering ,Turbo code ,General Physics and Astronomy ,Constant-weight code ,Code rate ,Low-density parity-check code ,Error detection and correction ,Algorithm ,Hamming code ,Parity bit - Abstract
We propose semi-analytical approaches for estimating the failure rate of interleaved error correction code (ECC) for parity-check (PC)-coded optical recording systems. We demonstrate the accuracy of the proposed approaches using simulation results. We further evaluate the ECC failure rate (EFR) of a PC-coded optical recording system. The analysis shows that with optimum interleaving degrees, the 4-bit constrained PC code achieves a gain of 0.6 dB over the rate 9/13 code without parity at EFR =10-16.
- Published
- 2008
38. Synthesis and Characteristics of a Phase-Change Magnetic Material
- Author
-
Xiang-Shui Miao, Luping Shi, Chong-Tow Chong, and Wen-Dong Song
- Subjects
Phase transition ,Phase change ,Materials science ,Condensed matter physics ,Ferromagnetism ,Mechanics of Materials ,Mechanical Engineering ,Magnet ,General Materials Science - Published
- 2008
39. The impact of membrane surface charges on the ion transport in MoS2 nanopore power generators.
- Author
-
Zhuo Huang, Yan Zhang, Tomoki Hayashida, Ziwei Ji, Yuhui He, Makusu Tsutsui, Xiang Shui Miao, and Masateru Taniguchi
- Subjects
OSMOTIC coefficients ,NANOPORES ,SURFACE chemistry ,ELECTRIC admittance ,NANOSTRUCTURED materials - Abstract
Recent experiments demonstrated giant osmotic effects induced in a single-atomic-layer MoS
2 nanopore by imposing a KCl concentration bias, thereby highlighting the prospect of ultrathin nanopores as power generators. In this work, we report on an electrokinetic analysis of the ionic transport in the MoS2 nanopore system. By taking membrane surface chemistry into account, we found profound roles of surface charges in and out of the nanopore on the cross-pore ion transport, which shed light on the intriguing experimental observations of a high pore conductance with a large open-circuit voltage in the MoS2 system. The present work establishes a theoretical model capable of dealing with ultrathin membrane surface charges for evaluating the energy conversion performance of nanopore power generators constructed with two-dimensional materials. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
40. Correlation analysis between the current fluctuation characteristics and the conductive filament morphology of HfO2-based memristor.
- Author
-
Yi Li, Kang-Sheng Yin, Mei-Yun Zhang, Long Cheng, Ke Lu, Shi-Bing Long, Yaxiong Zhou, Zhuorui Wang, Kan-Hao Xue, Ming Liu, and Xiang-Shui Miao
- Subjects
MEMRISTORS ,HAFNIUM oxide ,CURRENT fluctuations ,BURST noise ,ELECTRODES - Abstract
Memristors are attracting considerable interest for their prospective applications in nonvolatile memory, neuromorphic computing, and in-memory computing. However, the nature of resistance switching is still under debate, and current fluctuation in memristors is one of the critical concerns for stable performance. In this work, random telegraph noise (RTN) as the indication of current instabilities in distinct resistance states of the Pt/Ti/HfO
2 /W memristor is thoroughly investigated. Standard two-level digital-like RTN, multilevel current instabilities with non-correlation/correlation defects, and irreversible current transitions are observed and analyzed. The dependence of RTN on the resistance and read bias reveals that the current fluctuation depends strongly on the morphology and evolution of the conductive filament composed of oxygen vacancies. Our results link the current fluctuation behaviors to the evolution of the conductive filament and will guide continuous optimization of memristive devices. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
41. Identification of Vacancy Ratio in Crystalline GeTe Films
- Author
-
Fei Tong and Xiang Shui Miao
- Subjects
SQUID ,X-ray spectroscopy ,Crystallography ,Materials science ,chemistry ,X-ray photoelectron spectroscopy ,law ,Magnetism ,Vacancy defect ,chemistry.chemical_element ,Germanium ,law.invention - Abstract
XRD, XPS, SQUID and magnetism calculation based on spin-polarized DFT of GeTe crystalline films with different Co-doping have been studied to identify the vacancies in GeTe. The results show that Co occupies Ge vacancy and forms Co-Te bond, and confirm 8% vacancy ratio in GeTe.
- Published
- 2011
42. Impact of Water-Depletion Layer on Transport in Hydrophobic Nanochannels.
- Author
-
Yuhui He, Makusu Tsutsui, Xiang Shui Miao, and Masateru Taniguchi
- Published
- 2015
- Full Text
- View/download PDF
43. Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography.
- Author
-
Ri Wen Ni, Bi Jian Zeng, Jun Zhu Huang, Teng Luo, Zhen Li, and Xiang Shui Miao
- Subjects
THIN films ,CRYSTALLIZATION ,LITHOGRAPHY ,GERMANIUM compounds ,ANTIMONY - Abstract
Maskless phase-change lithographic technology is developed as a photoresist of phase-change materials. The controllable growth behavior of the crystallization region on an amorphous thin film of Ge2Sb2Te5 (GST) irradiated by a laser beam is investigated; the GST thin film is deposited on a silicon substrate by the sputtering method. The results of a series of the experiments and the simulations all show that the width of a crystalline pattern is not only closely related to laser power and pulse duration, but also is apparently affected by the interactive area between the focused laser spot and thin film. The width maintains a nonlinear growth with the enhancement of the laser power until the thin film approaches melting, whereas it gradually reaches a constant value due to the local thermal equilibrium. This equilibrium makes the width irrelevant to the moving velocity with certain constraints when the laser works in continuous-wave mode. Within a defocus range of 15 µm, the widths of the crystalline patterns are obtained in a broad range from 690 nm to 8.13 µm under a 0.4-NA objective lens. By adjusting the defocus amount, some crystalline square patterns with expected widths in a wide range are fabricated, and the mean percentage error between the expected and fabricated widths is only 1.495%. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
44. Effect of AlN Film on the Magnetic Properties of Rare Earth-Transition Metal Film
- Author
-
Zheng-qi, Lu, primary, Lee), Li Zuo-yi (Z Y, additional, Yuan-kai, Zheng, additional, Xiang-shui, Miao, additional, Zuo-qi, Hu, additional, Geng-qi, Lin, additional, Wei-zhong, Liu, additional, Rui, Xiong, additional, and Ke, Wang, additional
- Published
- 1997
- Full Text
- View/download PDF
45. Modelling of dual-port computing operations of a phase-change memory cell.
- Author
-
Hao Zhang, Rui-Hao Zhao, Fan Zhang, Zhen Li, and Xiang-Shui Miao
- Subjects
HEAT transfer ,CRYSTAL growth ,RC circuits ,RESISTANCE to change ,CELLS ,HEAT storage devices - Abstract
The general model of a phase-change memory (PCM) cell is very complex due to electrical property, thermal transfer and crystal growth. In this paper the general model is equivalent to an RC circuit, via which the dependence of the cell resistance on the number of pulses (Set or Reset) was investigated. Moreover, as for dual-port asynchronous operations of a pore-type PCM cell, a double-capacitor-based cell model was proposed. By simulation on the model we verified feasibility of the cell’s logic and arithmetic operations. In addition, the simulation results of addition and subtraction show that the resistance changes linearly with a short pulse sequence. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
46. GGA-1/2 self-energy correction for accurate band structure calculations: the case of resistive switching oxides.
- Author
-
Jun-Hui Yuan, Qi Chen, Leonardo R C Fonseca, Ming Xu, Kan-Hao Xue, and Xiang-Shui Miao
- Published
- 2018
- Full Text
- View/download PDF
47. Reconfigurable logic in nanosecond Cu/GeTe/TiN filamentary memristors for energy-efficient in-memory computing.
- Author
-
Miao-Miao Jin, Long Cheng, Yi Li, Si-Yu Hu, Ke Lu, Jia Chen, Nian Duan, Zhuo-Rui Wang, Ya-Xiong Zhou, Ting-Chang Chang, and Xiang-Shui Miao
- Subjects
MEMRISTORS ,TITANIUM nitride ,SWITCHING circuits - Abstract
Owing to the capability of integrating the information storage and computing in the same physical location, in-memory computing with memristors has become a research hotspot as a promising route for non von Neumann architecture. However, it is still a challenge to develop high performance devices as well as optimized logic methodologies to realize energy-efficient computing. Herein, filamentary Cu/GeTe/TiN memristor is reported to show satisfactory properties with nanosecond switching speed (<60 ns), low voltage operation (<2 V), high endurance (>10
4 cycles) and good retention (>104 s @85 °C). It is revealed that the charge carrier conduction mechanisms in high resistance and low resistance states are Schottky emission and hopping transport between the adjacent Cu clusters, respectively, based on the analysis of current–voltage behaviors and resistance–temperature characteristics. An intuitive picture is given to describe the dynamic processes of resistive switching. Moreover, based on the basic material implication (IMP) logic circuit, we proposed a reconfigurable logic method and experimentally implemented IMP, NOT, OR, and COPY logic functions. Design of a one-bit full adder with reduction in computational sequences and its validation in simulation further demonstrate the potential practical application. The results provide important progress towards understanding of resistive switching mechanism and realization of energy-efficient in-memory computing architecture. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
48. Reprogrammable logic in memristive crossbar for in-memory computing.
- Author
-
Long Cheng, Mei-Yun Zhang, Yi Li, Ya-Xiong Zhou, Zhuo-Rui Wang, Si-Yu Hu, Shi-Bing Long, Ming Liu, and Xiang-Shui Miao
- Subjects
CROSSBAR switches (Electronics) ,LOGIC circuits ,VON Neumann architecture (Computers) - Abstract
Memristive stateful logic has emerged as a promising next-generation in-memory computing paradigm to address escalating computing-performance pressures in traditional von Neumann architecture. Here, we present a nonvolatile reprogrammable logic method that can process data between different rows and columns in a memristive crossbar array based on material implication (IMP) logic. Arbitrary Boolean logic can be executed with a reprogrammable cell containing four memristors in a crossbar array. In the fabricated Ti/HfO
2 /W memristive array, some fundamental functions, such as universal NAND logic and data transfer, were experimentally implemented. Moreover, using eight memristors in a 2 × 4 array, a one-bit full adder was theoretically designed and verified by simulation to exhibit the feasibility of our method to accomplish complex computing tasks. In addition, some critical logic-related performances were further discussed, such as the flexibility of data processing, cascading problem and bit error rate. Such a method could be a step forward in developing IMP-based memristive nonvolatile logic for large-scale in-memory computing architecture. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
49. Effects of Thickness and Temperature on Thermoelectric Properties of Bi2Te3-Based Thin Films.
- Author
-
Dong-Dong Yang, Hao Tong, Ling-Jun Zhou, and Xiang-Shui Miao
- Subjects
BISMUTH compounds ,EFFECT of temperature on metals ,THICKNESS measurement ,THERMOELECTRICITY ,METALLIC thin films ,SILICA - Abstract
Bi
2 Te3 thin films and GeTe/B2 Te3 superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric (TE) measurements indicate that optimal thickness and thickness ratio improve the TE performance of Bi2 Te3 thin films and GeTe/B2 Te3 superlattices, respectively. High TE performances with figure-of-merit (ZT) values as high as 1.32 and 1.56 are achieved at 443 K for 30 nm and 50 nm Bi2 Te3 thin films, respectively. These ZT values are higher than those of p-type Bi2 Te3 alloys as reported. Relatively high ZT of the GeTe/B2 Te3 superlattices at 300–380 K were 0.62–0.76. The achieved high ZT value may be attributed to the unique nano- and micro-structures of the films, which increase phonon scattering and reduce thermal conductivity. The results indicate that Bi2 Te3 -based thin films can serve as high-performance materials for applications in TE devices. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
50. Temperature dependence of SET switching characteristics in phase-change memory cells.
- Author
-
Qiang He, Zhen Li, Chang Liu, Xiang-ru Meng, Ju-hong Peng, Zhi-bo Lai, and Xiang-shui Miao
- Subjects
CRYSTALLIZATION kinetics ,PHASE change materials ,HIGH density storage ,AMORPHIZATION ,COMPLEMENTARY metal oxide semiconductors - Abstract
The temperature dependence of crystallization kinetics of phase-change materials raises a series of reliability issues, while phase-change memory cells work at high temperature or thermal-disturbance condition. These issues hinder the development of ultrahigh-density storage devices. We investigate the evolution of SET switching characteristics of phase-change memory cells at high operating temperature. We show that the high temperature strongly impacts the SET state resistance. As a result, SET failure has been observed with elevated ambient temperature. Our SPICE simulations indicate that transient amorphization behavior during a complete SET pulse period is considered as the potential mechanism of SET failure. By modifying the SET pulse intensity and width linearly, we successfully reduce the SET failure in the experiments. The results illustrate that the demonstrated linear properties may optimize SET pulse performance. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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