The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
H Philip S Wong - One of the best experts on this subject based on the ideXlab platform.
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on the Switching Parameter variation of metal oxide rram part ii model corroboration and device design strategy
IEEE Transactions on Electron Devices, 2012Co-Authors: Ximeng Guan, H Philip S WongAbstract:Using the model developed in Part I of this two-part paper, the simulated dc sweep and pulse transient characteristics of a metal oxide resistive random access memory cell are corroborated with the experimental data of HfOx memory. Key Switching features such as the abrupt SET process, gradual RESET process, current fluctuation in the RESET process, and multilevel resistance state distributions are captured by the simulation. The current fluctuation in the RESET process is caused by the competition between the simultaneous oxygen vacancy recombination and generation processes. The origin of the high-resistance state variation and the tail bit problem are attributed to the variation of the tunneling gap distances and the stochastic nature of new Vo generation in the tunneling gap region, respectively. The use of the write-verify technique and a bilayer oxide structure are proposed to achieve a tighter resistance distribution.
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on the Switching Parameter variation of metal oxide rram part i physical modeling and simulation methodology
IEEE Transactions on Electron Devices, 2012Co-Authors: Ximeng Guan, Shimeng Yu, H Philip S WongAbstract:The variation of Switching Parameters is one of the major challenges to both the scaling and volume production of metal-oxide-based resistive random-access memories (RRAMs). In this two-part paper, the source of such Parameter variation is analyzed by a physics-based simulator, which is equipped with the capability to simulate a large number ( ~1000) of cyclic SET-RESET operations. By comparing the simulation results with experimental data, it is found that the random current fluctuation experimentally observed in the RESET processes is caused by the competition between trap generation and recombination, whereas the variation of the high resistance states and the tail bits are directly correlated to the randomness of the trap dynamics. A combined strategy with a bilayer dielectric material and a write-verification technique is proposed to minimize the resistance variation. We describe the simulation methodology and discuss the dc results in Part I. The corroboration of the model and the device optimization strategy will be discussed in Part II.
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on the stochastic nature of resistive Switching in metal oxide rram physical modeling monte carlo simulation and experimental characterization
International Electron Devices Meeting, 2011Co-Authors: Ximeng Guan, H Philip S WongAbstract:The origin of Switching Parameter variations in metal oxide resistive Switching random access memory (RRAM) is studied. The stochastic formation/rupture of the conductive filaments (CFs) is modeled and incorporated with a trap-assisted-tunneling (TAT) current solver. The experimental DC I–V characteristics and pulse transient waveform featuring the current fluctuation during the reset process are reproduced by Monte Carlo simulations. It is found that the wide spread of high resistance states (HRS) are due to the variation of tunneling gap distances, and the tail bits of the HRS are due to the newly generated traps near the electrode at the end of the reset process. To solve the over-reset and tail bits problems, a device structure with active/buffer bi-layer oxides combined with the reset-verify technique is proposed. Our model is corroborated by measured experimental data of HfO x based RRAM.
Ximeng Guan - One of the best experts on this subject based on the ideXlab platform.
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on the Switching Parameter variation of metal oxide rram part ii model corroboration and device design strategy
IEEE Transactions on Electron Devices, 2012Co-Authors: Ximeng Guan, H Philip S WongAbstract:Using the model developed in Part I of this two-part paper, the simulated dc sweep and pulse transient characteristics of a metal oxide resistive random access memory cell are corroborated with the experimental data of HfOx memory. Key Switching features such as the abrupt SET process, gradual RESET process, current fluctuation in the RESET process, and multilevel resistance state distributions are captured by the simulation. The current fluctuation in the RESET process is caused by the competition between the simultaneous oxygen vacancy recombination and generation processes. The origin of the high-resistance state variation and the tail bit problem are attributed to the variation of the tunneling gap distances and the stochastic nature of new Vo generation in the tunneling gap region, respectively. The use of the write-verify technique and a bilayer oxide structure are proposed to achieve a tighter resistance distribution.
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on the Switching Parameter variation of metal oxide rram part i physical modeling and simulation methodology
IEEE Transactions on Electron Devices, 2012Co-Authors: Ximeng Guan, Shimeng Yu, H Philip S WongAbstract:The variation of Switching Parameters is one of the major challenges to both the scaling and volume production of metal-oxide-based resistive random-access memories (RRAMs). In this two-part paper, the source of such Parameter variation is analyzed by a physics-based simulator, which is equipped with the capability to simulate a large number ( ~1000) of cyclic SET-RESET operations. By comparing the simulation results with experimental data, it is found that the random current fluctuation experimentally observed in the RESET processes is caused by the competition between trap generation and recombination, whereas the variation of the high resistance states and the tail bits are directly correlated to the randomness of the trap dynamics. A combined strategy with a bilayer dielectric material and a write-verification technique is proposed to minimize the resistance variation. We describe the simulation methodology and discuss the dc results in Part I. The corroboration of the model and the device optimization strategy will be discussed in Part II.
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On the Switching Parameter Variation of Metal-Oxide RRAM—Part I: Physical Modeling and Simulation Methodology
IEEE Transactions on Electron Devices, 2012Co-Authors: Ximeng Guan, H.-s. Philip WongAbstract:The variation of Switching Parameters is one of the major challenges to both the scaling and volume production of metal-oxide-based resistive random-access memories (RRAMs). In this two-part paper, the source of such Parameter variation is analyzed by a physics-based simulator, which is equipped with the capability to simulate a large number ( ~1000) of cyclic SET-RESET operations. By comparing the simulation results with experimental data, it is found that the random current fluctuation experimentally observed in the RESET processes is caused by the competition between trap generation and recombination, whereas the variation of the high resistance states and the tail bits are directly correlated to the randomness of the trap dynamics. A combined strategy with a bilayer dielectric material and a write-verification technique is proposed to minimize the resistance variation. We describe the simulation methodology and discuss the dc results in Part I. The corroboration of the model and the device optimization strategy will be discussed in Part II.
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on the stochastic nature of resistive Switching in metal oxide rram physical modeling monte carlo simulation and experimental characterization
International Electron Devices Meeting, 2011Co-Authors: Ximeng Guan, H Philip S WongAbstract:The origin of Switching Parameter variations in metal oxide resistive Switching random access memory (RRAM) is studied. The stochastic formation/rupture of the conductive filaments (CFs) is modeled and incorporated with a trap-assisted-tunneling (TAT) current solver. The experimental DC I–V characteristics and pulse transient waveform featuring the current fluctuation during the reset process are reproduced by Monte Carlo simulations. It is found that the wide spread of high resistance states (HRS) are due to the variation of tunneling gap distances, and the tail bits of the HRS are due to the newly generated traps near the electrode at the end of the reset process. To solve the over-reset and tail bits problems, a device structure with active/buffer bi-layer oxides combined with the reset-verify technique is proposed. Our model is corroborated by measured experimental data of HfO x based RRAM.
P. V. R. L. Narasimham - One of the best experts on this subject based on the ideXlab platform.
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Optimal Parameters of OUPFC and GUPFC Under Renewable Energy Power Variation Using Cuckoo Search Algorithm Variants
Journal of Electrical Engineering & Technology, 2020Co-Authors: K. V. Kumar Kavuturu, P. V. R. L. NarasimhamAbstract:Introduction In this paper, improved variants of cuckoo search algorithm are proposed for optimizing the controlling variables of flexible ac transmission system devices towards voltage stability enhancement and active power loss minimization by considering renewable energy sources intermittency in the network. Materials and methods Primarily, the optimal location for flexible ac transmission system devices is determined using line stability index and later the control Parameters of generalized unified power flow controller and optimal unified power flow controller are optimized at different intermittency levels of renewable energy sources using three cuckoo search algorithm variants. The case studies are performed on standard IEEE 14-, 30-, 57-bus test systems. Conclusion The superiority of proposed cuckoo search algorithm variants (linearly increased Switching Parameter, exponentially increased Switching Parameter and increased Switching Parameter in a power of three) in solving the multi-objective, non-linear complex optimization problem over time varying acceleration coefficient—particle swarm optimization variants is presented by illustrating various case studies.
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Transmission Security Enhancement under (N−1) Contingency Conditions with Optimal Unified Power Flow Controller and Renewable Energy Sources Generation
Journal of Electrical Engineering & Technology, 2020Co-Authors: K. V. Kumar Kavuturu, P. V. R. L. NarasimhamAbstract:Introduction Transmission system security management under (N−1) line contingency is one of the typical and essential tasks in power system operation and control. This paper examines the impact of the optimal unified power flow controller (OUPFC) and renewable energy sources (RES) on the severity of (n−1) line contingency on transmission system security. Materials and methods To test the performance of OUPFC device under single line contingency conditions, an optimal power flow (OPF) based multi-objective function is formulated using real power loss and line collapse proximity indicator (LCPI). Primarily, the optimal location of the OUPFC is determined using LCPI index and then (n−1) contingency analysis is performed by considering OUPFC device at different RES generation levels. Here, the control variables of OUPFC, tap-changers, VAr injections, output power of conventional energy sources (CES), bus voltages and bus angles are optimized with two different variants of the cuckoo search algorithm (CSA) namely (1) dynamically increasing Switching Parameter in power of three (CSA1) and (2) exponentially increasing Switching Parameter (CSA2). Conclusion The simulation results of various case studies on a standard IEEE-30 bus test system have shown the superiority of CSA2 in solving the multi-objective, non–linear complex optimization problem over CSA1 and time-varying acceleration coefficient-particle swarm optimization (TVAC-PSO). Also, the ability of OUPFC for managing the impact of (n−1) line contingency and variable RES generation is shown in terms of decreased real power loss, improved voltage profile and enhanced security margin.
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Transmission Security Enhancement under (N−1) Contingency Conditions with Optimal Unified Power Flow Controller and Renewable Energy Sources Generation
Journal of Electrical Engineering & Technology, 2020Co-Authors: K. V. Kumar Kavuturu, P. V. R. L. NarasimhamAbstract:Transmission system security management under (N−1) line contingency is one of the typical and essential tasks in power system operation and control. This paper examines the impact of the optimal unified power flow controller (OUPFC) and renewable energy sources (RES) on the severity of (n−1) line contingency on transmission system security. To test the performance of OUPFC device under single line contingency conditions, an optimal power flow (OPF) based multi-objective function is formulated using real power loss and line collapse proximity indicator (LCPI). Primarily, the optimal location of the OUPFC is determined using LCPI index and then (n−1) contingency analysis is performed by considering OUPFC device at different RES generation levels. Here, the control variables of OUPFC, tap-changers, VAr injections, output power of conventional energy sources (CES), bus voltages and bus angles are optimized with two different variants of the cuckoo search algorithm (CSA) namely (1) dynamically increasing Switching Parameter in power of three (CSA1) and (2) exponentially increasing Switching Parameter (CSA2). The simulation results of various case studies on a standard IEEE-30 bus test system have shown the superiority of CSA2 in solving the multi-objective, non–linear complex optimization problem over CSA1 and time-varying acceleration coefficient-particle swarm optimization (TVAC-PSO). Also, the ability of OUPFC for managing the impact of (n−1) line contingency and variable RES generation is shown in terms of decreased real power loss, improved voltage profile and enhanced security margin.
Ming Liu - One of the best experts on this subject based on the ideXlab platform.
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Carrier-transport-path-induced Switching Parameter fluctuation in oxide-based resistive Switching memory
Materials Research Express, 2015Co-Authors: Nianduan Lu, Writam Banerjee, Pengxiao Sun, Hangbing Lv, Shibing Long, Ling Li, Ming Wang, Qi Liu, Ming LiuAbstract:Akey challenge in resistive Switching memory is to reduce the Switching Parameter fluctuation, which always affects the stability and reliability of an RS device. Numerous methods have been carried out for improving the fluctuation of the Switching Parameter. However, because the physical nature of the Switching Parameter fluctuation is, to date, not well understood, a universal identification of the Switching Parameter fluctuation still has not be achieved. Based on the activation energy of carrier transport from the first-principles calculations, we present a physical model. This proposed model is considering the macroscopic fluctuating I-Vcurve and material microstructure to analyze the characteristics of carrier transport and the origin of Switching Parameter fluctuations. The proposed model may specially identify the defect energy level and quantify the distribution of the Switching Parameter. The model provides possible clues for improving the uniformity of the Switching Parameter as well.
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set statistics in conductive bridge random access memory device with cu hfo2 pt structure
Applied Physics Letters, 2014Co-Authors: Meiyun Zhang, Shibing Long, Qi Liu, Guoming Wang, Xiaojuan Lian, E Miranda, J Sune, Ming LiuAbstract:The Switching Parameter variation of resistive Switching memory is one of the most important challenges in its application. In this letter, we have studied the set statistics of conductive bridge random access memory with a Cu/HfO2/Pt structure. The experimental distributions of the set Parameters in several off resistance ranges are shown to nicely fit a Weibull model. The Weibull slopes of the set voltage and current increase and decrease logarithmically with off resistance, respectively. This experimental behavior is perfectly captured by a Monte Carlo simulator based on the cell-based set voltage statistics model and the Quantum Point Contact electron transport model. Our work provides indications for the improvement of the Switching uniformity.
H.-s. Philip Wong - One of the best experts on this subject based on the ideXlab platform.
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On the Switching Parameter Variation of Metal-Oxide RRAM—Part I: Physical Modeling and Simulation Methodology
IEEE Transactions on Electron Devices, 2012Co-Authors: Ximeng Guan, H.-s. Philip WongAbstract:The variation of Switching Parameters is one of the major challenges to both the scaling and volume production of metal-oxide-based resistive random-access memories (RRAMs). In this two-part paper, the source of such Parameter variation is analyzed by a physics-based simulator, which is equipped with the capability to simulate a large number ( ~1000) of cyclic SET-RESET operations. By comparing the simulation results with experimental data, it is found that the random current fluctuation experimentally observed in the RESET processes is caused by the competition between trap generation and recombination, whereas the variation of the high resistance states and the tail bits are directly correlated to the randomness of the trap dynamics. A combined strategy with a bilayer dielectric material and a write-verification technique is proposed to minimize the resistance variation. We describe the simulation methodology and discuss the dc results in Part I. The corroboration of the model and the device optimization strategy will be discussed in Part II.
