The thermo-electric behavior of shape memory alloy （SMA） wire was presented. When the wire was electrically heated above its transformation temperature by current, a large mechanical force is exerted due to transfor...The thermo-electric behavior of shape memory alloy （SMA） wire was presented. When the wire was electrically heated above its transformation temperature by current, a large mechanical force is exerted due to transformation in its phases. In order to make use of SMA wire as an actuator, different parameters and their relationships were investigated. These parameters are recoverable strain （displacement）, temperature hysteresis and electrical resistance variation under different stress levels. Optimum safe heating current was assessed and phase transformation temperatures were estimated by heat transfer model. The wire was heated and cooled by 680 mA of current for 796 s under natural air convection. The strain recovered is 4.33% and corresponding change in resistance is 11.2% at 43 MPa of stress. The resistance variation shows linearly with displacement and current during heating and cooling cycle respectively. This study will be useful in precisely controlling of SMA wire actuator with and without external sensor feedback.展开更多
Resistive switching random access memories(RRAM)have been considered to be promising for future information technology with applications for non-volatile memory,logic circuits and neuromorphic computing.Key performanc...Resistive switching random access memories(RRAM)have been considered to be promising for future information technology with applications for non-volatile memory,logic circuits and neuromorphic computing.Key performances of those resistive devices are approaching the realistic levels for production.In this paper,we review the progress of valence change type memories,including relevant work reported by our group.Both electrode engineering and in-situ transmission electron microscopy(TEM)high-resolution observation have been implemented to reveal the influence of migration of oxygen anions/vacancies on the resistive switching effect.The understanding of resistive memory mechanism is significantly important for device applications.展开更多
Resistive random access memory(RRAM) with crossbar structure is receiving widespread attentions due to its simple structure,high density,and feasibility of three-dimensional(3D) stack.It is an extremely promising solu...Resistive random access memory(RRAM) with crossbar structure is receiving widespread attentions due to its simple structure,high density,and feasibility of three-dimensional(3D) stack.It is an extremely promising solution for high density storage.However,a major issue of crosstalk restricts its development and application.In this paper,we will first introduce the integration methods of RRAM device and the existing crosstalk phenomenon in passive crossbar array,and then focus on the 1D1R(one diode and one resistor) structure and self-rectifying 1R(one resistor) structure which can restrain crosstalk and avoid misreading for the passive crossbar array.The test methods of crossbar array are also presented to evaluate the performances of passive crossbar array to achieve its commercial application in comparison with the active array consisting of one transistor and one RRAM cell(1T1R) structure.Finally,the future research direction of rectifying-based RRAM passive crossbar array is discussed.展开更多
文摘The thermo-electric behavior of shape memory alloy （SMA） wire was presented. When the wire was electrically heated above its transformation temperature by current, a large mechanical force is exerted due to transformation in its phases. In order to make use of SMA wire as an actuator, different parameters and their relationships were investigated. These parameters are recoverable strain （displacement）, temperature hysteresis and electrical resistance variation under different stress levels. Optimum safe heating current was assessed and phase transformation temperatures were estimated by heat transfer model. The wire was heated and cooled by 680 mA of current for 796 s under natural air convection. The strain recovered is 4.33% and corresponding change in resistance is 11.2% at 43 MPa of stress. The resistance variation shows linearly with displacement and current during heating and cooling cycle respectively. This study will be useful in precisely controlling of SMA wire actuator with and without external sensor feedback.
文摘Resistive switching random access memories(RRAM)have been considered to be promising for future information technology with applications for non-volatile memory,logic circuits and neuromorphic computing.Key performances of those resistive devices are approaching the realistic levels for production.In this paper,we review the progress of valence change type memories,including relevant work reported by our group.Both electrode engineering and in-situ transmission electron microscopy(TEM)high-resolution observation have been implemented to reveal the influence of migration of oxygen anions/vacancies on the resistive switching effect.The understanding of resistive memory mechanism is significantly important for device applications.
基金supported by the National Basic Research Program of China ("973" Project) (Grant Nos. 2011CB309602, 2010CB934200, 2008CB925002)the National Natural Science Foundation of China (Grant Nos. 60825403, 50972160)+1 种基金the Hi-Tech Research and Development Program of China ("863" Project) (Grant No. 2009AA03Z306)the National Key Project (Grant No. 2009ZX02023-005-4)
文摘Resistive random access memory(RRAM) with crossbar structure is receiving widespread attentions due to its simple structure,high density,and feasibility of three-dimensional(3D) stack.It is an extremely promising solution for high density storage.However,a major issue of crosstalk restricts its development and application.In this paper,we will first introduce the integration methods of RRAM device and the existing crosstalk phenomenon in passive crossbar array,and then focus on the 1D1R(one diode and one resistor) structure and self-rectifying 1R(one resistor) structure which can restrain crosstalk and avoid misreading for the passive crossbar array.The test methods of crossbar array are also presented to evaluate the performances of passive crossbar array to achieve its commercial application in comparison with the active array consisting of one transistor and one RRAM cell(1T1R) structure.Finally,the future research direction of rectifying-based RRAM passive crossbar array is discussed.
