摩擦力显微镜(friction force microscopy,FFM)是一种基于摩擦力信号的原子力显微镜,能够对二维材料晶格进行快速、无损的高分辨成像.然而,由于热漂移、黏附力、表面静电等因素的影响,环境条件下二维材料的高分辨FFM成像仍面临着巨大挑...摩擦力显微镜(friction force microscopy,FFM)是一种基于摩擦力信号的原子力显微镜,能够对二维材料晶格进行快速、无损的高分辨成像.然而,由于热漂移、黏附力、表面静电等因素的影响,环境条件下二维材料的高分辨FFM成像仍面临着巨大挑战.基于以上问题,本文以高定向热解石墨为标准样品,通过对探针在样品表面黏滑行为的分析,系统研究了探针弹性常数、正应力和扫描速度对高分辨FFM成像的影响,并建立了一套可靠的二维材料晶格结构表征方法.该方法能够获得精确的结构信息,所测得的二维材料晶格常数平均误差小于2.3%.此外,该方法还适用于化学气相沉积法和剥离法制备的多种二维材料,展现出较高的普适性.本文的研究结果为环境条件下二维材料晶格结构的精确表征提供了新思路.展开更多
The non-Markov process exists widely in thermodymanic process,while it usually requires the packing of many transistors and memories with great system complexity in a traditional device structure to minic such functio...The non-Markov process exists widely in thermodymanic process,while it usually requires the packing of many transistors and memories with great system complexity in a traditional device structure to minic such functions.Two-dimensional(2D)material-based resistive random access memory(RRAM)devices have the potential for next-generation computing systems with much-reduced complexity.Here,we achieve a non-Markov chain in an individual RRAM device based on 2D mineral material mica with a vertical metal/mica/metal structure.We find that the potassium ions(K+)in 2D mica gradually move in the direction of the applied electric field,making the initially insulating mica conductive.The accumulation of K+is changed by an electric field,and the 2D-mica RRAM has both single and double memory windows,a high on/off ratio,decent stability,and repeatability.This is the first time a non-Markov chain process has been established in a single RRAM,in which the movement of K+is dependent on the stimulated voltage as well as their past states.This work not only uncovers an intrinsic inner ionic conductivity of 2D mica,but also opens the door for the production of such RRAM devices with numerous functions and applications.展开更多
Two-dimensional(2D)transition metal chalcogenides(TMCs)are promising for nanoelectronics and energy applications.Among them,the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surfa...Two-dimensional(2D)transition metal chalcogenides(TMCs)are promising for nanoelectronics and energy applications.Among them,the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surface and strong intralayer and interlayer bonding.However,the synthesis of non-layered 2D TMCs is challenging and this has made it difficult to study their structures and properties at thin thickness limit.Here,we develop a universal dual-metal precursors method to grow non-layered TMCs in which a mixture of a metal and its chloride serves as the metal source.Taking hexagonal Fe_(1-x)S as an example,the thickness of the Fe_(1-x)S flakes is down to 3 nm with a lateral size of over 100 μm.Importantly,we find ordered cation Fe vacancies in Fe_(1-x)S,which is distinct from layered TMCs like MoS_(2) where anion vacancies are commonly observed.Low-temperature transport measurements and theoretical calculations show that 2D Fe_(1-x)S is a stable semiconductor with a narrow bandgap of60 meV.In addition to Fe_(1-x)S,the method is universal in growing various non-layered 2D TMCs containing ordered cation vacancies,including Fe_(1-x)Se,Co_(1-x)S,Cr_(1-x)S,and V_(1-x)S.This work paves the way to grow and exploit properties of non-layered materials at 2D thickness limit.展开更多
基金financial supports from the National Science Foundation of China for Distinguished Young Scholars (52125309)the National Natural Science Foundation of China (52188101)+5 种基金Guangdong Basic and Applied Basic Research Foundation (2022B1515120004)Guangdong Innovative and Entrepreneurial Research Team Program (2017ZT07C341)the Innovation Team Project of the Department of Education of Guangdong Province (2023KCXTD051)Shenzhen Basic Research Project (WDZC20220812141108001)Tsinghua Shenzhen International Graduate School-Shenzhen Pengrui Young Faculty Program of Shenzhen Pengrui Foundation (SZPR2023002)Banting Postdoctoral Fellowships Program (01353-000)。
文摘摩擦力显微镜(friction force microscopy,FFM)是一种基于摩擦力信号的原子力显微镜,能够对二维材料晶格进行快速、无损的高分辨成像.然而,由于热漂移、黏附力、表面静电等因素的影响,环境条件下二维材料的高分辨FFM成像仍面临着巨大挑战.基于以上问题,本文以高定向热解石墨为标准样品,通过对探针在样品表面黏滑行为的分析,系统研究了探针弹性常数、正应力和扫描速度对高分辨FFM成像的影响,并建立了一套可靠的二维材料晶格结构表征方法.该方法能够获得精确的结构信息,所测得的二维材料晶格常数平均误差小于2.3%.此外,该方法还适用于化学气相沉积法和剥离法制备的多种二维材料,展现出较高的普适性.本文的研究结果为环境条件下二维材料晶格结构的精确表征提供了新思路.
基金This work was supported by the National Natural Science Foundation of China(51920105002,51991340,51722206,and 51991343)Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)+1 种基金the Bureau of Industry and Information Technology of Shenzhen for the“2017 Graphene Manufacturing Innovation Center Project”(201901171523)the Shenzhen Basic Research Program(JCYJ20200109144620815 and JCYJ20200109144616617).
文摘The non-Markov process exists widely in thermodymanic process,while it usually requires the packing of many transistors and memories with great system complexity in a traditional device structure to minic such functions.Two-dimensional(2D)material-based resistive random access memory(RRAM)devices have the potential for next-generation computing systems with much-reduced complexity.Here,we achieve a non-Markov chain in an individual RRAM device based on 2D mineral material mica with a vertical metal/mica/metal structure.We find that the potassium ions(K+)in 2D mica gradually move in the direction of the applied electric field,making the initially insulating mica conductive.The accumulation of K+is changed by an electric field,and the 2D-mica RRAM has both single and double memory windows,a high on/off ratio,decent stability,and repeatability.This is the first time a non-Markov chain process has been established in a single RRAM,in which the movement of K+is dependent on the stimulated voltage as well as their past states.This work not only uncovers an intrinsic inner ionic conductivity of 2D mica,but also opens the door for the production of such RRAM devices with numerous functions and applications.
基金supported by the National Science Fund for Distinguished Young Scholars(52125309)the National Natural Science Foundation of China(51991343,51920105002,51991340,52188101,and 11974156)+3 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341 and 2019ZT08C044)the Bureau of Industry and Information Technology of Shenzhen for the “2017 Graphene Manufacturing Innovation Center Project”(201901171523)Shenzhen Basic Research Project(JCYJ20200109144616617 and JCYJ20190809180605522)Shenzhen Science and Technology Program(KQTD20190929173815000 and 20200925161102001)。
文摘Two-dimensional(2D)transition metal chalcogenides(TMCs)are promising for nanoelectronics and energy applications.Among them,the emerging non-layered TMCs are unique due to their unsaturated dangling bonds on the surface and strong intralayer and interlayer bonding.However,the synthesis of non-layered 2D TMCs is challenging and this has made it difficult to study their structures and properties at thin thickness limit.Here,we develop a universal dual-metal precursors method to grow non-layered TMCs in which a mixture of a metal and its chloride serves as the metal source.Taking hexagonal Fe_(1-x)S as an example,the thickness of the Fe_(1-x)S flakes is down to 3 nm with a lateral size of over 100 μm.Importantly,we find ordered cation Fe vacancies in Fe_(1-x)S,which is distinct from layered TMCs like MoS_(2) where anion vacancies are commonly observed.Low-temperature transport measurements and theoretical calculations show that 2D Fe_(1-x)S is a stable semiconductor with a narrow bandgap of60 meV.In addition to Fe_(1-x)S,the method is universal in growing various non-layered 2D TMCs containing ordered cation vacancies,including Fe_(1-x)Se,Co_(1-x)S,Cr_(1-x)S,and V_(1-x)S.This work paves the way to grow and exploit properties of non-layered materials at 2D thickness limit.
